JP2007327991A - Zoom lens and imaging apparatus with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a zoom lens advantageous for satisfying both of the thinning of a lens system when being collapsed and housed and the securement of an f-number showing a bright condition. <P>SOLUTION: When varying power from a wide angle end to a telephoto end, space between first and second lens groups G1 and G2 is narrowed and space between the second and the third lens groups G2 and G3 is widened. The first lens group G1 comprises one single lens, which is a biconcave negative lens, or two lenses, that is, a biconcave negative lens and a positive lens, and the second lens group comprises two positive lenses and one negative lens. At least either of the two positive lenses of the second lens group has an aspherical lens surface. The zoom lens satisfies a conditional expression (1): 16<C<SB>jw</SB>/h<SB>1w</SB><23 (provided that h<SB>1w</SB>means the height of an axial marginal light beam on the incident surface of the first lens group at the wide angle end in the longest distance focused state, and C<SB>jw</SB>means length on an optical axis to an image surface from the incident surface of the first lens group at the wide angle end in the longest distance focused state). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a zoom lens and an image pickup apparatus including the same, and more particularly to a bright zoom lens that is advantageous for thinning when retracted. The present invention also relates to an imaging apparatus such as a digital camera or a video camera provided with an electronic imaging element that converts an image formed on an imaging surface into an electrical signal.

  Due to the recent downsizing of digital cameras, it is essential that the size when not in use is reduced. In particular, the size in the thickness direction is required to be reduced. Therefore, the imaging optical system of the camera is also required to be retractable and retractable in the thickness direction when not in use.

  On the other hand, as the miniaturization of the camera and the increase in the number of pixels of the image sensor progress, the pixel pitch of the image sensor progresses further, the sensitivity is limited due to the decrease in the SN ratio, and subject blurring and camera shake are likely to occur. There is.

  In addition, the market demands not only to cope with these blurs, but also to increase the environment in which photographing can be performed with respect to a conventional camera and to cope with photographing low-illuminance subjects.

  As a method corresponding to these, there are a method for reducing camera shake using a mechanical correction mechanism, a method for increasing the sensitivity of the image sensor and increasing the shutter speed, and the like.

  However, in the method of correcting blur by mechanically moving a part of the photographic lens or the image sensor, the exposure time becomes long and cannot cope with the blur of the subject. To cope with this, a complicated control mechanism (for example, Therefore, it is necessary to move the shooting position in accordance with the movement of the subject or to correct the image by electrical calculation after shooting).

  On the other hand, higher sensitivity of the image sensor can cope with both subject blur and camera shake, but image quality is likely to deteriorate due to noise of the image sensor.

  Therefore, it is effective for solving these problems to reduce (brighten) the F-number of the photographing lens and increase the amount of incident light to the image sensor.

  However, a conventional bright zoom lens having a minimum F-number of 1.8 class has a complicated lens configuration, and it has been difficult to ensure a sufficient thinness when retracted to be mounted on a compact camera.

  Accordingly, an object of the present invention, which will be described later, is to provide a bright zoom lens having a small F number that can be mounted on a thin compact camera.

  In general, it is known that a zoom lens of a type in which the first lens unit has a positive refractive power is advantageous for constituting a bright F-number zoom lens. However, since the first lens group becomes large in the radial direction and the number of lenses is likely to increase, it is unsuitable for retracting and storing thinly when not in use.

  On the other hand, as a configuration of an optical system that can be stored compactly when not in use, a zoom lens of a type in which a first lens unit has a negative refractive power is known.

  This type of zoom lens is used in many thin cameras because it can be retracted and retracted more thinly than a zoom lens of the type preceded by a lens unit having a positive refractive power.

  However, a conventional zoom lens preceded by a lens unit having a negative refractive power does not achieve both a reduction in thickness when retracted and a bright F number.

  For example, in the zoom lens described in Patent Document 1 in which the number of lenses is small and a thin lens frame can be configured, the F number is as dark as about 2.9. Therefore, it is disadvantageous for obtaining a sufficient amount of light.

On the other hand, the zoom lenses described in Patent Document 2, Patent Document 3, Patent Document 4, and Patent Document 5 that realize a bright F-number have a large number of lenses and are difficult to retract compactly. .
JP 2004-318099 A JP-A-4-114116 Japanese Patent Laid-Open No. 1-40913 JP 2001-42218 A JP 2001-208969 A

  The present invention has been made in view of such problems of the prior art, and an object of the present invention is to provide a zoom lens that is advantageous in achieving both a reduction in the thickness of the lens system when retracted and securing a bright F number. It is.

  It is another object of the present invention to provide a small-sized imaging device that is thinned when the zoom lens is retracted.

The zoom lens according to the first aspect of the present invention that achieves the above object, in order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a positive refractive power. Each of the first lens group, the second lens group, and the third lens group moves along the optical axis during zooming from the wide-angle end to the telephoto end, The distance between the first lens group and the second lens group is narrowed, the distance between the second lens group and the third lens group is widened, and the first lens group is a biconcave negative lens 1 The second lens group is composed of two positive lenses and one negative lens, and the two positive lenses of the second lens group. Among the lenses, at least one positive lens has an aspheric lens surface,
The following conditional expression is satisfied.

16 <C _jw / h _1w <23 (1)
Here, h _1w is the height of the on-axis marginal ray at the entrance surface of the first lens group at the wide-angle end and the farthest distance in-focus state,
C _jw is the length on the optical axis from the first lens group entrance surface to the image plane in the wide-angle end and the farthest distance in-focus state,
It is.

The zoom lens according to the second aspect of the present invention includes, in order from the object side, a first lens group having negative refractive power, a second lens group having positive refractive power, and a third lens having positive refractive power. Each of the first lens group, the second lens group, and the third lens group moves along an optical axis during zooming from the wide-angle end to the telephoto end, and the first lens group The distance between the second lens group is narrowed, the distance between the second lens group and the third lens group is widened, and the first lens group is a single lens that is a biconcave negative lens, or both The second lens group is composed of two positive lenses and one negative lens, and at least of the two positive lenses in the second lens group. One positive lens has an aspheric lens surface,
The following conditional expression is satisfied.

1.5 <f ₂ / f _w <1.9 (5)
Where f ₂ is the focal length of the second lens group,
f _w is the focal length of the entire zoom lens system at the wide-angle end and at the farthest distance,
It is.

The zoom lens according to the third aspect of the present invention includes, in order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens having a positive refractive power. Each of the first lens group, the second lens group, and the third lens group moves along an optical axis during zooming from the wide-angle end to the telephoto end, and the first lens group The distance between the second lens group is narrowed, the distance between the second lens group and the third lens group is widened, and the first lens group is a single lens that is a biconcave negative lens, or both The second lens group is composed of two positive lenses and one negative lens, and at least of the two positive lenses in the second lens group. One positive lens has an aspheric lens surface,
The following conditional expression is satisfied.

0.4 <h _1w /IH<0.5 (8)
Here, h _1w is the height of the on-axis marginal ray at the entrance surface of the first lens group at the wide-angle end and the farthest distance in-focus state,
IH is the maximum image height,
It is.

  Below, the reason and effect | action which take the said structure in this invention are demonstrated.

  The zoom lens of the present invention is common to the first to third side surfaces, and in order from the object side, the first lens group having a negative refractive power, the second lens group having a positive refractive power, and the positive refractive power. The third lens group has a lens type.

  Then, during zooming from the wide-angle end to the telephoto end, each of the first lens group, the second lens group, and the third lens group moves along the optical axis, and between the first lens group and the second lens group. The zooming movement method is such that the distance is narrow and the distance between the second lens group and the third lens group is wide.

  The first lens group includes one single lens that is a biconcave negative lens, or two lenses, a biconcave negative lens and a positive lens, and the second lens group includes two positive lenses and one lens. A negative lens is formed, and at least one of the two positive lenses of the second lens group has an aspheric lens surface.

  In this way, the negative lens group is used as the first lens group, and the negative refractive power precedes the type configuration, thereby reducing the diameter of the first lens group and facilitating downsizing.

  Then, the two lens groups having a positive refractive power, which are arranged subsequent to the first lens group, have the above-described movement method, so that the second lens group has a zooming function during zooming. The lens group can have a function of adjusting the imaging position.

  At this time, by moving the first, second, and third lens groups, respectively, the influence of higher-order spherical aberration and coma aberration due to the increased light incident height on the lens surface when the F number is made brighter. Can be adjusted easily.

  The first lens group is composed of a single lens of a double-concave negative lens or a double lens of a double-concave negative lens and a positive lens, so that the size reduction and the aberration balance can be maintained well when retracted. It will be advantageous.

  In the first lens group, the height of the off-axis light beam near the wide-angle end increases. Therefore, it is advantageous for miniaturization by reducing the number of constituent lenses of the first lens group as much as possible to suppress the thickness on the optical axis. In other words, considering the case where the number of lenses in the first lens group is increased, the light beam height on the wide-angle side becomes higher and the effective diameter on the object side of the first lens group becomes larger. The on-axis thickness and off-axis thickness tend to increase, which is disadvantageous for downsizing.

  Moreover, by making the shape of the negative lens a biconcave shape, it is possible to suppress the protrusion at the lens peripheral portion with respect to the lens central portion and to suppress the increase in the thickness of the first lens group. Further, when the lens configuration is small (bright) with a small F number, the height of the on-axis marginal ray increases. In such a case, the influence of spherical aberration and coma becomes conspicuous. Therefore, by adopting the above-described configuration so that the entrance surface of the negative lens of the first lens group is concave, negative power is shared between the entrance surface and the exit surface of the negative lens of the first lens group, and a negative power surface. Is reduced (the radius of curvature is reduced) to suppress the occurrence of spherical aberration and coma, thereby making it easy to improve the overall aberration balance.

  If the first lens unit is composed of a single biconcave single lens, it is advantageous for miniaturization when retracted.

  If the first lens group is composed of a biconcave negative lens and a positive lens, the influence of chromatic aberration can be reduced (if this positive lens has a meniscus shape with a convex surface facing the negative lens side, The thickness can be reduced, which is advantageous for aberration correction.)

  The second lens group includes two positive lenses and one negative lens, and at least one positive lens has an aspheric lens surface. With such a configuration, it is advantageous for the second lens group to be mainly responsible for the imaging action and the zooming action. That is, it is easy to suppress the occurrence of spherical aberration and the like by sharing the positive power in the second lens group between the two lenses. By disposing a negative lens in the second lens group, it becomes easy to cancel and correct spherical aberration, axial chromatic aberration, and the like generated by the two positive lenses. In addition, using an aspherical surface for the positive lens is advantageous in correcting spherical aberration and coma aberration while having a bright F-number (if this aspherical surface has a smaller refractive power in the periphery than near the optical axis). The aspherical surface is preferably used for the convex surface of the positive lens of the second lens group, and more preferably used for a plurality of convex surfaces).

  The zoom lens according to the first aspect of the present invention satisfies the following conditional expression.

16 <C _jw / h _1w <23 (1)
Here, h _1w is the height of the on-axis marginal ray at the entrance surface of the first lens group at the wide-angle end and the farthest distance in-focus state,
C _jw is the length on the optical axis from the first lens group entrance surface to the image plane in the wide-angle end and the farthest distance in-focus state,
It is.

  This condition defines the relationship between the total length of an appropriate lens system for collapsing in a compact manner while maintaining good imaging performance at the wide-angle end and the height of the marginal ray on the entrance surface of the first lens group. is there. In a zoom lens of a type preceded by a lens unit having a negative refractive power as in the present invention (positioned closest to the object side), the on-axis marginal ray height in the second lens unit and subsequent lens units becomes high. By avoiding falling below the lower limit of 16 in the conditional expression (1), the axial marginal ray height can be suppressed, or the entire zoom lens length at the wide angle end can be secured to suppress the refractive power in each lens group. The amount of spherical aberration generated in both the first lens group and the second lens group is reduced, and it becomes easy to design both the on-axis aberration and the off-axis aberration well. Alternatively, in order to obtain a desired zooming effect by the second lens group, the amount of movement of the second lens group to the object side can be reduced, and the overall length of the zoom lens at the telephoto end can be easily suppressed.

  In addition, it is preferable not to exceed the upper limit of 23 in the conditional expression (1) so as to prevent the F-number at the wide-angle end from becoming too large and to ensure brightness. Alternatively, the total length at the time of wide-angle end photography can be suppressed, the amount of the first lens group that is fed out by switching from the retracted state to the used state can be reduced, and the lens frame for the retracting can be made thin.

  Furthermore, it is preferable that the following conditional expression is satisfied.

16 <C _jmax / h _1w <23 (2)
Where C _jmax is the length when the length on the optical axis from the first lens group entrance surface to the image plane in the entire use state is the longest,
It is.

  The maximum extension amount of the lens frame depends on the length when the lens total length (the length on the optical axis from the first lens group incident surface to the image plane) is the longest in all use states. It is preferable to satisfy the above-mentioned conditions in order to moderately suppress the number of lens frames and the size in the optical axis direction necessary for retracting housing.

  The lower limit 16 of the conditional expression (2) is not reduced, and the overall length is prevented from becoming smaller in all use conditions, which is advantageous for securing a zoom ratio and optical performance (aberration correction). preferable. It is preferable not to exceed the upper limit of 23 in the conditional expression (2) so as to suppress the maximum value of the total lens length, suppress the increase in the number of rings of the lens frame, or suppress the dimension in the optical axis direction.

  When the entire lens length (the length on the optical axis from the first lens group incident surface to the image plane) is the longest in the state of focusing at the farthest distance at the wide-angle end, it has the same meaning as conditional expression (1). Become.

  Further, in any one of the zoom lenses described above, there is an aperture stop disposed at any position from the space immediately before the second lens group to the space immediately after the second lens group. It is preferable that the aperture stop be configured to move in the optical axis direction integrally with the second lens group during zooming. This is advantageous in reducing the diameter of the zoom lens, moving the exit pupil away from the image plane, and improving the aberration balance.

  For example, when the aperture stop is located after the third lens group, the entrance pupil position near the wide-angle end becomes deep (the distance from the entrance surface of the first lens group to the entrance pupil becomes long). For this reason, when it is attempted to secure the angle of view and the amount of peripheral light within the image plane, the diameter of the lens constituting the first lens group becomes large, and the thickness of the first lens group (thickness on the optical axis and the thickness at the periphery). And it becomes difficult to retract in a compact manner. In addition, the exit pupil is likely to approach the image plane, and the incident angle of the off-axis light beam incident on the image sensor increases, so that shading is likely to occur.

  On the other hand, when the aperture stop is arranged near the first lens group, the incident position of the off-axis light beam on the second lens group, which bears a part of the imaging function, is increased, and the incident position is greatly changed by the zooming operation. Will do. For this reason, the aberration variation in the second lens group becomes large, and it becomes difficult to obtain good imaging performance while maintaining a bright F number over the entire zoom range from the wide-angle end to the telephoto end.

  In any one of the zoom lenses described above, it is preferable that the following conditional expression is satisfied.

0.25 <h _1'w / f _w <0.4 (3)
Where h _1′w is the height of the axial marginal ray at the exit surface of the first lens group at the wide-angle end and in the farthest distance focus state,
f _w is the focal length of the entire zoom lens system at the wide-angle end and at the farthest distance,
It is.

  This conditional expression defines the relationship between the focal length at the wide-angle end and the farthest distance in-focus state and the appropriate height of the on-axis marginal ray on the exit surface of the first lens group. The axial marginal ray height on the exit side surface of the first lens group is suppressed so as not to exceed the upper limit of 0.4 of the conditional expression (3), and spherical aberration generated in the first lens group is suppressed. preferable. It is preferable to ensure sufficient brightness so as not to fall below the lower limit of 0.25 of the conditional expression (3).

  More preferably, an aspheric surface is provided in the first lens group to suppress the occurrence of spherical aberration. Since the first lens group is a group in which the variation of the incident light height and the incident angle due to zooming is large, an aspherical surface is arranged so as to suppress the influence on the curvature of field and the distortion, which is favorable in the entire zoom lens system. It is preferable to have an aberration balance.

  Specifically, it is preferable that the aspherical surface has a shape in which the refractive power is larger in the vicinity (weaker negative or positive refractive power) than the negative refractive power in the vicinity of the optical axis. This aspherical surface is preferably provided on the object side surface of the biconcave negative lens, so that the occurrence of distortion on the wide angle side can be reduced. Furthermore, it is more preferable to provide an aspherical surface on the plurality of concave surfaces of the first lens group, since the aspherical shape can be prevented from becoming an extreme shape, and deterioration of imaging performance due to decentering can be easily suppressed.

  In any one of the zoom lenses described above, it is preferable that the following conditional expression is satisfied.

1.0 <Σd / f _w <2.2 (4)
Where Σd is the sum of the thickness on the optical axis of each lens group of the entire zoom lens system,
f _w is the focal length of the entire zoom lens system at the wide-angle end and at the farthest distance,
It is.

  This conditional expression prescribes the sum of the thicknesses of the respective lens groups for realizing a compact collapsed thickness. It is preferable not to exceed the upper limit of 2.2 of conditional expression (4) so as to suppress the sum of the thicknesses of the lens groups on the optical axis and to suppress the thickness of the lens frame when retracted. The thickness on the optical axis of each lens group is appropriately secured so as not to fall below 1.0, which is the lower limit of conditional expression (4), and the positive refractive power of the second and third lens groups is secured. It is preferable to facilitate. This makes it easy to suppress the amount of movement of each lens group for obtaining a desired zoom ratio. As a result, it is advantageous for downsizing the lens barrel part for movement.

  In any one of the zoom lenses described above, it is preferable that the fourth lens group including one aspherical lens is disposed on the image side of the third lens group.

  The zoom lens according to the present invention has a single-concave negative lens or a two-lens configuration in which a positive lens is added to the first lens group in a simple configuration. By adopting the biconcave shape, it is easy to suppress the influence of spherical aberration while maintaining the negative refractive power of the lens group as well as downsizing when retracting. This is advantageous for correcting spherical aberration, which is important when a bright F number is used. On the other hand, it is difficult to correct distortion and field curvature simultaneously with correction of spherical aberration. Therefore, by introducing a fourth lens group consisting of one aspherical lens on the image side of the third lens group, the fourth lens group bears the correction of the distortion aberration of off-axis aberration and the curvature of field. The overall aberration balance can be improved.

  Furthermore, it is more preferable for the fourth lens group to have a positive or negative refractive power paraxially for fine adjustment of the aberration (specifically, this aspherical surface is near the optical axis. By making the shape in which the refractive power is smaller in the periphery than the refractive power, it is effective in correcting off-axis aberrations caused by the negative power of the first lens group. Is a positive or negative shape with a weak refractive power near the optical axis when the refractive power near the optical axis is a positive convex surface, and a refractive power around the optical axis when the refractive power near the optical axis is a negative concave surface Means a strongly negative shape).

  Further, it is preferable to perform a focusing operation from the farthest distance focus state to the short distance focus state by moving the third lens group in the optical axis direction with any of the zoom lenses described above. . By adopting the inner focus method by moving the third lens group, the weight of the driving lens can be reduced compared with the case where the first lens group having a large diameter is driven, and a high-speed focusing operation is possible. Further, it is preferable that the angle of view change in the focusing operation is smaller than when the second lens group is a focus group.

  Furthermore, it is preferable that the third lens group has one positive lens or two positive lenses and a negative lens because the thickness can be reduced when the lens barrel is retracted and the weight burden of focusing drive can be reduced.

  Further, when the fourth lens group is arranged, the farthest distance focusing is achieved by moving the third lens group and the fourth lens group in the optical axis direction with the mutual distance being constant or changing the mutual distance. It is preferable to perform a focusing operation from the state to the short distance in-focus state. By adopting the inner focus method by moving the third lens group, the weight of the driving lens can be reduced compared with the case where the first lens group having a large diameter is driven, and a high-speed focusing operation is possible. Further, it is preferable that the angle of view change in the focusing operation is smaller than when the second lens group is a focus group.

  Furthermore, it is preferable that the third lens group has one positive lens or two positive lenses and a negative lens because the thickness can be reduced when the lens barrel is retracted and the weight burden of focusing drive can be reduced.

  Further, it is possible to drive the focus while correcting the curvature of field caused by the fluctuation of the object distance by the movement of the fourth lens group accompanying the movement of the third lens group, and it is preferable because good imaging characteristics can be obtained up to the closest distance. .

  Furthermore, it is preferable that the third lens group has one positive lens or two positive lenses and a negative lens, which can reduce the thickness when retracted and reduce the burden of focusing driving.

  The zoom lens configuration of the first aspect described above, and the more preferable configuration described in parentheses, can be more effective by satisfying the zoom lens of the second and third aspects shown below at the same time. This is preferable.

The zoom lens according to the second aspect of the present invention includes, in order from the object side, a first lens group having negative refractive power, a second lens group having positive refractive power, and a third lens having positive refractive power. And having a group
During zooming from the wide-angle end to the telephoto end, each of the first lens group, the second lens group, and the third lens group moves along the optical axis, and the distance between the first lens group and the second lens group is increased. The distance between the second lens group and the third lens group increases,
The first lens group consists of a single lens that is a biconcave negative lens, or two lenses, a biconcave negative lens and a positive lens, and the second lens group consists of two positive lenses and one negative lens. Thus, at least one of the two positive lenses in the second lens group has an aspheric lens surface.

  The technical effects of these points are as described above.

  And it is characterized by satisfying the following conditional expression.

1.5 <f ₂ / f _w <1.9 (5)
Where f ₂ is the focal length of the second lens group,
f _w is the focal length of the entire zoom lens system at the wide-angle end and at the farthest distance,
It is.

  Conditional expression (5) defines an appropriate refractive power of the second lens group in order to obtain good imaging performance while maintaining a compact overall length. By ensuring that the refractive power of the second lens group is not exceeded so as not to exceed the upper limit of 1.9 of conditional expression (6), it becomes easy to suppress the overall length of the lens system. In addition, it is advantageous for securing the zooming effect in the second lens group, it is easy to suppress the movement amount at the time of zooming, the lens frame for movement can be reduced in size, and it is advantageous for downsizing when retracted.

  By making sure that the lower limit of 1.5 of the conditional expression (6) is not exceeded, it is easy to suppress the amount of aberration generated in the second lens group, and good imaging performance is maintained over the entire zoom range while maintaining a bright F number. It is advantageous to ensure.

  Furthermore, it is preferable to satisfy the following conditions.

1.09 <| f ₁ | / (f _w · F _NOw ) <1.7 (6)
Where f ₁ is the focal length of the first lens group,
F _NOw is the F number at the wide-angle end and at the farthest distance.
It is.

  Conditional expression (6) defines an appropriate refractive power of the first lens unit for obtaining a bright F number. By making sure that the upper limit of 1.7 is not exceeded, the negative refractive power of the first lens group is secured, and the overall length of the zoom lens at the wide-angle end can be easily suppressed. It is also advantageous for downsizing when retracted. By preventing the lowering of the lower limit of 1.09 and suppressing the increase in refractive power with respect to the axial marginal ray height of the first lens group, it becomes easy to balance spherical aberration with other aberrations.

  Moreover, it is preferable that the following conditional expressions are satisfied.

0.28 <h _2w / f ₂ <0.35 (7)
Where h _2w is the height of the on-axis marginal ray at the entrance surface of the second lens group at the wide-angle end and at the farthest distance focus state,
It is.

  Conditional expression (7) defines an appropriate ratio between the marginal ray height of the second lens group and the focal length of the second lens group. By not exceeding the upper limit of 0.35, the size of the diameter of the second lens group can be suppressed, and it is advantageous to reduce the thickness of the second lens group and the thickness when retracted. Further, by making it not below the lower limit of 0.28, it becomes easy to secure the refractive power in the second lens group and suppress the increase in the total length of the zoom lens. Further, the amount of lens movement for retracting can be suppressed. For example, the radial direction of the lens frame can be reduced by reducing the number of frame members.

  In addition, it is preferable that the fourth lens group including one aspherical lens is provided on the image side of the third lens group.

  The zoom lens according to the present invention has a single-concave negative lens or a two-lens configuration in which a positive lens is added to the first lens group in a simple configuration. By adopting the biconcave shape, it is easy to suppress the influence of spherical aberration while maintaining the negative refractive power of the lens group as well as downsizing when retracting. This is advantageous for correcting spherical aberration, which is important when a bright F number is used. On the other hand, it is difficult to correct distortion and field curvature simultaneously with correction of spherical aberration. Therefore, by introducing a fourth lens group consisting of one aspherical lens on the image side of the third lens group, the fourth lens group bears the correction of off-axis aberration distortion and field curvature. Aberration balance can be improved.

  Furthermore, it is more preferable for the fourth lens group to have a positive or negative refractive power paraxially in order to finely adjust the aberration (specifically, this aspherical surface is located near the optical axis. The shape in which the refractive power is smaller in the periphery than the refractive power is effective in correcting off-axis aberrations caused by the negative power of the first lens group. When the refractive power near the optical axis is a positive convex surface, the shape has a negative or negative refractive power around the optical axis. When the refractive power near the optical axis is a negative concave surface, the refractive power is strong around the optical axis. Means a negative shape).

  Further, it is preferable to perform a focusing operation from the farthest distance focusing state to the short distance focusing state by moving the third lens group in the optical axis direction.

  By adopting the inner focus method by moving the third lens group, the weight of the driving lens can be reduced compared with the case where the first lens group having a large diameter is driven, and a high-speed focusing operation is possible. Further, it is preferable that the angle of view change in the focusing operation is smaller than when the second lens group is a focus group.

  In addition, by moving the third lens group and the fourth lens group in the optical axis direction with the mutual interval being constant or changing the mutual interval, the farthest distance focusing state is changed to the short-distance focusing state. It is preferable to perform a focusing operation.

  By adopting the inner focus method by moving the third lens group, the weight of the driving lens can be reduced compared with the case where the first lens group having a large diameter is driven, and a high-speed focusing operation is possible. Further, it is preferable that the angle of view change in the focusing operation is smaller than when the second lens group is a focus group.

  The zoom lens according to the third aspect of the present invention includes, in order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens having a positive refractive power. Each of the first lens group, the second lens group, and the third lens group moves along an optical axis during zooming from the wide-angle end to the telephoto end, and the first lens group The distance between the second lens group is narrowed, the distance between the second lens group and the third lens group is widened, and the first lens group is a single lens that is a biconcave negative lens, or both The second lens group is composed of two positive lenses and one negative lens, and at least of the two positive lenses in the second lens group. One positive lens has an aspheric lens surface.

  The technical effects of these points are as described above.

And it is characterized by satisfying the following conditional expression.
Have
0.4 <h _1w /IH<0.5 (8)
Here, h _1w is the height of the on-axis marginal ray at the entrance surface of the first lens group at the wide-angle end and the farthest distance in-focus state,
IH is the maximum image height,
It is.

  Conditional expression (8) defines an appropriate entrance pupil size with respect to the maximum image height in order to maintain a bright F-number and good imaging performance. In a zoom lens of a type preceded by a lens unit having a negative refractive power as in the present invention (positioned closest to the object side), the on-axis marginal ray height in the second lens unit and subsequent lens units becomes high.

  By making sure that the lower limit of 0.4 of conditional expression (8) is not exceeded, it is advantageous for securing a bright F number. Alternatively, by suppressing the image height, it becomes easy to suppress the amount of distortion generated in the first lens group. By avoiding exceeding the upper limit of 0.5 of the conditional expression (8), it is possible to suppress the axial light beam diameter, to easily suppress spherical aberration in the first lens group, and to balance aberration correction with curvature of field. This makes it easier to design to maintain good imaging performance over the entire zoom range. Further, it is advantageous for securing the angle of view at the wide angle end.

  In some cases, the field stop just before the imaging surface or the imaging area of the imaging device can be changed. When such an imaging area changes, the largest image height in the range that can be taken as the imaging area is set to the maximum image height. IH.

  When an image sensor that obtains image information by photoelectric conversion such as CCD or CMOS is used as the image sensor, the maximum image height IH is the maximum image height in the effective image area.

  The effective imaging area means an area used for reproducing and printing a captured image in an area where the photoelectric conversion surface of the imaging element is arranged.

  Furthermore, it is preferable that the following conditional expression is satisfied.

0.8 <h _2w /IH<1.2 (9)
Where h _2w is the height of the on-axis marginal ray at the entrance surface of the second lens group at the wide-angle end and at the farthest distance focus state,
It is.

  Conditional expression (9) defines the marginal ray height in the second lens group appropriate for maintaining good imaging performance and the size of the lens. When the second lens group has the lens configuration of the present invention, it is easy to have a main image forming function. For this reason, the incident height of the on-axis marginal ray on the second lens group is likely to be highest in the second lens group. Therefore, it is possible to suppress an increase in the diameter of the zoom lens in the radial direction with respect to the size of the imaging surface and the imaging element, and to suppress the diameter of the lens frame without exceeding the upper limit of 1.2 of the conditional expression (9). preferable. In addition, the thickness of the second lens group on the optical axis is suppressed, which is advantageous for downsizing when retracted.

  By ensuring that the lower limit of 0.8 in conditional expression (9) is not exceeded, the image forming action of the second lens group is ensured, and the burden of the image forming function after the third lens group is suppressed, thereby reducing the number of lenses. It is easy to reduce and is advantageous for shortening the thickness when retracted. Or, it is advantageous for securing the F number.

  Moreover, it is preferable that the following conditional expressions are satisfied.

0.4 <D _2w / f _w <1.0 (10)
Where D _2w is the distance on the optical axis between the second lens group and the third lens group at the wide-angle end and in the farthest distance focusing state,
f _w is the focal length of the entire zoom lens system at the wide-angle end and at the farthest distance,
It is.

  Conditional expression (10) sets an appropriate distance between the second and third lens units at the wide angle end. By making sure that the upper limit of 1.0 is not exceeded, the total length of the zoom lens at the wide-angle end can be easily suppressed. Alternatively, it is easy to suppress an increase in the marginal ray height of the second lens group in order to ensure brightness, and it is easy to suppress an increase in the lens thickness of the second lens group. Also, by making sure that the lower limit of 0.4 is not exceeded, it is advantageous for correcting curvature of field. Furthermore, it is advantageous for securing a moving space when the third lens group performs a focusing operation.

  Moreover, it is preferable that the following conditional expressions are satisfied.

0.4 <g _3w / g _3t <0.88 (11)
Where g _3w is the height of the most off-axis principal ray at the entrance surface of the third lens group at the wide-angle end and the farthest distance in-focus state,
g _3t is the height of the most off-axis principal ray at the entrance surface of the third lens group at the telephoto end and at the farthest distance focused state;
It is.

  Conditional expression (11) sets the appropriate incident light height of the off-axis light beam to the third lens group. In the configuration of the present invention, the first lens unit is made as simple as possible in order to reduce the thickness when retracted. In the case of such a configuration, it becomes difficult to satisfactorily correct the distortion due to the distortion and the curvature of field in the first lens group by the first lens group itself. Therefore, by appropriately varying the height of the off-axis chief ray incident on the third lens group depending on the zoom state, it becomes easy to correct uncorrected distortion and curvature of field generated in the first lens group. By avoiding exceeding the upper limit of 0.88 and the lower limit of 0.4 in the conditional expression (11), it becomes easy to correct fluctuation due to distortion and zooming of the field curvature.

  Furthermore, it is more preferable that the third lens group includes an aspherical surface in order to obtain this correction effect more satisfactorily.

  It is more preferable that the fourth lens group including one aspherical lens is provided on the image side of the third lens group.

  The zoom lens according to the present invention has a single-concave negative lens or a two-lens configuration in which a positive lens is added to the first lens group in a simple configuration. By adopting the biconcave shape, it is easy to suppress the influence of spherical aberration while maintaining the negative refractive power of the lens group as well as downsizing when retracting. This is advantageous for correcting spherical aberration, which is important when a bright F number is used. On the other hand, it is difficult to correct distortion and field curvature simultaneously with correction of spherical aberration. Therefore, by introducing a fourth lens group consisting of one aspherical lens on the image side of the third lens group, the fourth lens group bears the correction of the distortion aberration of off-axis aberration and the curvature of field. The overall aberration balance can be improved.

  Furthermore, it is more preferable for the fourth lens group to have a positive or negative refractive power paraxially for fine adjustment of the aberration (specifically, this aspherical surface is near the optical axis. By making the shape in which the refractive power is smaller in the periphery than the refractive power, it is effective in correcting off-axis aberrations caused by the negative power of the first lens group. Is a positive or negative shape with a weak refractive power near the optical axis when the refractive power near the optical axis is a positive convex surface, and a refractive power around the optical axis when the refractive power near the optical axis is a negative concave surface Means a strongly negative shape).

  Further, it is preferable to perform a focusing operation from the farthest distance focusing state to the short distance focusing state by moving the third lens group in the optical axis direction.

  By adopting the inner focus method by moving the third lens group, the weight of the driving lens can be reduced compared with the case where the first lens group having a large diameter is driven, and a high-speed focusing operation is possible. Further, it is preferable to reduce the change in the angle of view and the change in the driving amount in the focusing operation, compared with the case where the second lens group is the focus group.

  In addition, by moving the third lens group and the fourth lens group in the optical axis direction with the mutual interval being constant or changing the mutual interval, the farthest distance focusing state is changed to the short-distance focusing state. It is preferable to perform a focusing operation.

  By adopting the inner focus method by moving the third lens group, the weight of the driving lens can be reduced compared with the case where the first lens group having a large diameter is driven, and a high-speed focusing operation is possible. Further, it is preferable to reduce the change in the angle of view and the change in the driving amount in the focusing operation, compared with the case where the second lens group is the focus group.

  In the zoom lens according to the first to third aspects of the present invention, it is preferable that the following conditional expressions are satisfied.

2.3 <f _t / f _w <6.0 (12)
Where _fw is the focal length of the entire zoom lens system at the wide-angle end and the farthest distance focus state,
_ft is the focal length of the entire zoom lens system at the telephoto end and in the farthest distance focusing state,
It is.

  It is preferable to ensure the degree of freedom by changing the angle of view so as not to fall below the lower limit of 2.3 in conditional expression (12). In addition, it is preferable to ensure brightness at the telephoto end so as not to exceed the upper limit of 6.0.

  In addition, it is preferable that the zoom lenses according to the first to third aspects of the present invention satisfy the following conditional expressions.

56 ° <2ω _w <86 ° (13)
However, ω _w is the half angle of view of the entire zoom lens system at the wide-angle end and in the farthest distance focus state,
It is.

  It is preferable that the angle of view is secured so as not to fall below the lower limit of 56 ° of conditional expression (13), and the influence of camera shake at the wide-angle end is suppressed. In addition, it is preferable that the diameter of the first lens unit is prevented from being increased so as not to exceed the upper limit of 86 °, and the size of the first lens unit is reduced. Alternatively, it is preferable that the refractive power of each lens unit is not too strong, and the influence of aberration can be easily suppressed.

  In addition, it is preferable that the zoom lenses according to the first to third aspects of the present invention satisfy the following conditional expressions.

1.2 <D _12w / D _23w <20.0 (14)
Where D _12w is the distance on the optical axis between the first lens group and the second lens group at the wide-angle end and in the farthest distance focus state,
D _23w is the distance on the optical axis between the second lens group and the third lens group at the wide-angle end and in the farthest distance focus state;
It is.

  Ensuring a wide angle of view and ensuring the amount of change in the distance by arranging the first, second, and third lens groups like the retrofocus type so that the lower limit of 1.2 of conditional expression (14) is not exceeded. Therefore, it is preferable to secure a zoom ratio. In addition, it is preferable not to exceed the upper limit of 20.0, to prevent the distance between the second and third lens groups from becoming too small, and to ensure the function of moving the exit pupil away by the third lens group. Alternatively, it is preferable to prevent the distance between the first and second lens groups from becoming too long, and to suppress the increase in the overall length of the wide-angle end and the increase in the diameter of the first lens group.

  The above configurations and conditional expressions achieve individual effects by satisfying each individually, but satisfying a plurality at the same time is more preferable in terms of ensuring brightness, downsizing, high performance, etc. It is preferable to make it.

  It is preferable to limit the range of each conditional expression.

For conditional expression (1),
The lower limit is more preferably 17.5.
The upper limit is more preferably 22.5.

For conditional expression (2),
The lower limit is more preferably 17.5.
The upper limit is more preferably 22.5.

Conditional expression (3)
The lower limit is more preferably 0.254.
More preferably, the upper limit value is 0.37.

For conditional expression (4),
The lower limit is more preferably 1.20.
More preferably, the upper limit value is 2.1.

Conditional expression (5)
The lower limit is more preferably 1.55.

Conditional expression (8)
The lower limit value is more preferably 0.45.

Conditional expression (9)
More preferably, the lower limit is 0.85.
The upper limit is more preferably 1.15.

For conditional expression (10),
The lower limit value is more preferably 0.45.
More preferably, the upper limit is 0.98.

For conditional expression (11),
More preferably, the upper limit value is 0.8.

Conditional expression (12)
The lower limit is more preferably 2.8.
The upper limit is more preferably 5.0.

For conditional expression (13),
The lower limit is more preferably 60 °.
More preferably, the upper limit is 70 °.

For conditional expression (14),
More preferably, the lower limit is 2.0.
It is more preferable that the upper limit value is 8.0.

  It is more preferable that a plurality of the above conditions are satisfied simultaneously.

  In addition, an image pickup apparatus including any one of the zoom lenses described above and an image pickup element that is disposed on the image side of the zoom lens and converts an image formed by the zoom lens into an electric signal can be provided.

  According to the present invention, it is possible to provide a zoom lens that is advantageous in achieving both a reduction in the thickness of the lens system when retracted and securing a bright F number. Furthermore, it is possible to provide a small-sized imaging device by reducing the thickness when the zoom lens is retracted.

  Examples 1 to 15 of the zoom lens according to the present invention will be described below. Lens cross-sectional views at the wide-angle end (a), the intermediate state (b), and the telephoto end (c) during focusing on an object point at infinity in Examples 1 to 15 are shown in FIGS. In each figure, the first lens group is G1, the aperture stop is S, the second lens group is G2, the third lens group is G3, the fourth lens group is G4, and the optical low-pass filter with infrared cut coat is F. The cover glass of the electronic image sensor (CCD or CMOS) is indicated by C, and the image plane (light receiving surface of the electronic image sensor) is indicated by I. In addition, about an infrared cut coat, you may arrange | position an infrared cut absorption filter separately, or you may use what gave the multilayer film for a wavelength range restriction | limiting on the surface of the cover glass C. FIG. 1 to 15 also show the on-axis marginal ray and the most off-axis chief ray at the wide-angle end, the intermediate focal length state, and the telephoto end, respectively.

  As shown in FIG. 1, the zoom lens of Example 1 includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a positive refractive power, The fourth lens group G4 has a positive refractive power, and the brightness stop S is disposed integrally with the second lens group G2 on the object side of the second lens group G2. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves along a locus that is convex toward the image side, and is located closer to the image side than the wide-angle end position at the telephoto end. The aperture stop S and the second lens group G2 monotonously move toward the object side while integrally reducing the distance between the first lens group G1. The third lens group G3 moves to the image side while widening the distance from the second lens group G2. The fourth lens group G4 is fixed.

  In order from the object side, the first lens group G1 includes a biconcave negative lens and a biconvex positive lens, and the second lens group G2 includes a biconvex positive lens, a positive meniscus lens having a convex surface facing the object side, and an object. The third lens group G3 is composed of one biconvex positive lens, and the fourth lens group G4 is one positive meniscus lens having a convex surface facing the object side. Consists of.

  The aspheric surfaces are both surfaces of the biconcave negative lens of the first lens group G1, both surfaces of the biconvex positive lens of the second lens group G2, the image side surface of the biconvex positive lens of the third lens group G3, and the fourth lens group. It is used for six surfaces on the object side of the G4 positive meniscus lens.

  As shown in FIG. 2, the zoom lens according to the second embodiment includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a positive refractive power. The aperture stop S is arranged integrally with the second lens group G2 on the object side of the second lens group G2. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves along a locus that is convex toward the image side, and is located closer to the image side than the wide-angle end position at the telephoto end. The aperture stop S and the second lens group G2 monotonously move toward the object side while integrally reducing the distance between the first lens group G1. The third lens group G3 moves to the image side while widening the distance from the second lens group G2.

  In order from the object side, the first lens group G1 includes a biconcave negative lens and a biconvex positive lens, and the second lens group G2 includes a biconvex positive lens, a positive meniscus lens having a convex surface facing the object side, and an object. The third lens group G3 is composed of one biconvex positive lens. The cemented lens is a negative meniscus lens having a convex surface facing the side.

  The aspheric surfaces are used for the five surfaces of the double-concave negative lens of the first lens group G1, the double-convex positive lens of the second lens group G2, and the image side surface of the biconvex positive lens of the third lens group G3. ing.

  As shown in FIG. 3, the zoom lens of Example 3 includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a positive refractive power, The fourth lens group G4 has a positive refractive power, and the brightness stop S is disposed integrally with the second lens group G2 on the object side of the second lens group G2. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves along a locus that is convex toward the image side, and is located closer to the image side than the wide-angle end position at the telephoto end. The aperture stop S and the second lens group G2 monotonously move toward the object side while integrally reducing the distance between the first lens group G1. The third lens group G3 moves along a locus convex toward the object side while increasing the distance from the second lens group G2, and is located closer to the image side than the wide-angle end position at the telephoto end.

  In order from the object side, the first lens group G1 includes a biconcave negative lens and a biconvex positive lens, and the second lens group G2 includes a biconvex positive lens, and a cemented lens of a biconvex positive lens and a biconcave negative lens. The third lens group G3 is composed of one biconvex positive lens, and the fourth lens group G4 is composed of one convex flat positive lens having a convex surface facing the object side.

  The aspheric surfaces are both surfaces of the biconcave negative lens of the first lens group G1, both surfaces of the biconvex positive lens of the single lens of the second lens group G2, the image side surface of the biconvex positive lens of the third lens group G3, It is used for six surfaces on the object side of the convex flat positive lens of the four lens group G4.

  As shown in FIG. 4, the zoom lens of Example 4 includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a positive refractive power. The fourth lens group G4 has a positive refractive power, and the brightness stop S is disposed integrally with the second lens group G2 on the object side of the second lens group G2. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves along a locus that is convex toward the image side, and is located closer to the image side than the wide-angle end position at the telephoto end. The aperture stop S and the second lens group G2 monotonously move toward the object side while integrally reducing the distance between the first lens group G1. The third lens group G3 moves along a locus convex toward the object side while increasing the distance from the second lens group G2, and is located closer to the image side than the wide-angle end position at the telephoto end. The fourth lens group G4 moves to the image side while being narrowed from the intermediate state to the telephoto end while increasing the distance from the third lens group G3 from the wide-angle end to the intermediate state.

  In order from the object side, the first lens group G1 includes a biconcave negative lens and a positive meniscus lens having a convex surface facing the object side, and the second lens group G2 includes a biconvex positive lens, a biconvex positive lens, and both The third lens group G3 is composed of one biconvex positive lens, and the fourth lens group G4 is composed of one positive meniscus lens having a convex surface facing the image side.

  The aspheric surfaces are both surfaces of the biconcave negative lens of the first lens group G1, both surfaces of the biconvex positive lens of the single lens of the second lens group G2, the image side surface of the biconvex positive lens of the third lens group G3, It is used for six surfaces on the object side of the positive meniscus lens of the four lens group G4.

  As shown in FIG. 5, the zoom lens of Example 5 includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a positive refractive power. The fourth lens group G4 has a negative refractive power, and the aperture stop S is integrally disposed in the second lens group G2. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves along a locus that is convex toward the image side, and is located closer to the image side than the wide-angle end position at the telephoto end. The aperture stop S and the second lens group G2 monotonously move toward the object side while integrally reducing the distance between the first lens group G1. The third lens group G3 moves toward the object side while widening from the intermediate state to the telephoto end while slightly reducing the distance from the second lens group G2 from the wide-angle end to the intermediate state. The fourth lens group G4 moves along a locus convex toward the object side while increasing the distance from the third lens group G3, and is located closer to the image side than the wide-angle end position at the telephoto end.

  In order from the object side, the first lens group G1 is composed of a cemented lens of a biconcave negative lens and a positive meniscus lens having a convex surface facing the object side, and the second lens group G2 is a positive meniscus lens having a convex surface facing the object side. And an aperture stop S, a cemented lens of a negative meniscus lens having a convex surface facing the object side and a biconvex positive lens, and the third lens group G3 is composed of a single positive meniscus lens having a convex surface facing the object side. The fourth lens group G4 is composed of a single negative meniscus lens having a convex surface facing the image side.

  The aspherical surfaces are the most object side surface of the cemented lens of the first lens group G1, both surfaces of a single positive meniscus lens of the second lens group G2, both surfaces of the positive meniscus lens of the third lens group G3, and the fourth lens group. It is used for six surfaces on the image side of the negative meniscus lens of G4.

  As shown in FIG. 6, the zoom lens of Example 6 includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a positive refractive power, The fourth lens group G4 has a negative refractive power, and the brightness stop S is disposed integrally with the second lens group G2 on the image side of the second lens group G2. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves along a locus that is convex toward the image side, and is located closer to the image side than the wide-angle end position at the telephoto end. The second lens group G2 and the aperture stop S move monotonously toward the object side while reducing the distance between the first lens group G1 and the first lens group G2. The third lens group G3 moves toward the object side while widening from the intermediate state to the telephoto end while slightly reducing the distance from the second lens group G2 from the wide-angle end to the intermediate state. The fourth lens group G4 moves along a locus convex toward the object side while increasing the distance from the third lens group G3, and is located closer to the image side than the wide-angle end position at the telephoto end.

  In order from the object side, the first lens group G1 is composed of a cemented lens of a biconcave negative lens and a positive meniscus lens having a convex surface facing the object side, and the second lens group G2 is a positive meniscus lens having a convex surface facing the object side. And a negative meniscus lens having a convex surface facing the object side and a biconvex positive lens, and a cemented third lens. The third lens group G3 is composed of a single positive meniscus lens having a convex surface facing the object side. G4 includes one negative meniscus lens having a convex surface facing the image side.

  The aspherical surface is the most object side surface of the cemented lens of the first lens group G1, the most object side surface of the three-unit cemented lens of the second lens group G2, both surfaces of the positive meniscus lens of the third lens group G3, and the fourth. It is used on the five image-side surfaces of the negative meniscus lens in the lens group G4.

  As shown in FIG. 7, the zoom lens according to the seventh embodiment includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a positive refractive power. The fourth lens group G4 has a negative refractive power, and the aperture stop S is integrally disposed in the second lens group G2. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves along a locus that is convex toward the image side, and is located closer to the image side than the wide-angle end position at the telephoto end. The aperture stop S and the second lens group G2 monotonously move toward the object side while integrally reducing the distance between the first lens group G1. The third lens group G3 moves toward the object side while widening the distance from the second lens group G2. The fourth lens group G4 is fixed.

  In order from the object side, the first lens group G1 includes a cemented lens of a biconcave negative lens and a positive meniscus lens having a convex surface facing the object side. The second lens group G2 includes a biconvex positive lens and an aperture stop S. And a positive meniscus lens having a convex surface facing the object side and a negative meniscus lens having a convex surface facing the object side, and the third lens group G3 is composed of a single positive meniscus lens having a convex surface facing the object side. The fourth lens group G4 includes one negative meniscus lens having a convex surface directed toward the object side.

  The aspherical surfaces are the most object-side surface and the most image-side surface of the cemented lens of the first lens group G1, both surfaces of a single biconvex positive lens of the second lens group G2, and a positive meniscus lens of the third lens group G3. And 7 surfaces of the object side surface of the negative meniscus lens of the fourth lens group G4.

  As shown in FIG. 8, the zoom lens of Example 8 includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a positive refractive power, The fourth lens group G4 has a positive refractive power, and the brightness stop S is disposed integrally with the second lens group G2 on the object side of the second lens group G2. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves along a locus that is convex toward the image side, and is located closer to the image side than the wide-angle end position at the telephoto end. The aperture stop S and the second lens group G2 monotonously move toward the object side while integrally reducing the distance between the first lens group G1. The third lens group G3 moves along a locus convex toward the object side while increasing the distance from the second lens group G2, and is located closer to the image side than the wide-angle end position at the telephoto end. The fourth lens group G4 moves toward the image side while being slightly contracted from the intermediate state to the telephoto end while increasing the distance from the third lens group G3 from the wide-angle end to the intermediate state.

  In order from the object side, the first lens group G1 includes a cemented lens of a biconcave negative lens and a positive meniscus lens having a convex surface facing the object side. The second lens group G2 includes a biconvex positive lens and a convex surface facing the object side. A positive meniscus lens having a convex surface and a negative meniscus lens having a convex surface facing the object side. The third lens group G3 includes one biconvex positive lens, and the fourth lens group G4 has a convex surface on the image side. It consists of a single positive meniscus lens.

  The aspherical surfaces are the most object-side surface and the most image-side surface of the cemented lens of the first lens group G1, the double-convex positive lens of the single lens of the second lens group G2, and the biconvex positive of the third lens group G3. It is used for 6 surfaces of the image side surface of the lens and the object side surface of the positive meniscus lens of the fourth lens group G4.

  As shown in FIG. 9, the zoom lens of Example 9 includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a positive refractive power. The fourth lens group G4 has a positive refractive power, and the brightness stop S is disposed integrally with the second lens group G2 on the image side of the second lens group G2. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves along a locus that is convex toward the image side, and is located closer to the image side than the wide-angle end position at the telephoto end. The second lens group G2 and the aperture stop S move monotonously toward the object side while reducing the distance between the first lens group G1 and the first lens group G2. The third lens group G3 moves toward the object side while widening the distance from the second lens group G2. The fourth lens group G4 is fixed.

  In order from the object side, the first lens group G1 includes a cemented lens of a biconcave negative lens and a positive meniscus lens having a convex surface facing the object side. The second lens group G2 includes a biconvex positive lens and a biconvex positive lens. The third lens group G3 is composed of one positive meniscus lens having a convex surface facing the object side, and the fourth lens group G4 is composed of one biconvex positive lens.

  The aspherical surfaces are the most object-side surface and the most image-side surface of the cemented lens of the first lens group G1, both surfaces of a single biconvex positive lens of the second lens group G2, and a positive meniscus lens of the third lens group G3. And 7 surfaces of the object side surface of the biconvex positive lens of the fourth lens group G4.

  As shown in FIG. 10, the zoom lens of Example 10 includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a positive refractive power, The fourth lens group G4 has a negative refractive power, and the brightness stop S is disposed integrally with the second lens group G2 on the object side of the second lens group G2. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves along a locus that is convex toward the image side, and is located closer to the image side than the wide-angle end position at the telephoto end. The aperture stop S and the second lens group G2 monotonously move toward the object side while integrally reducing the distance between the first lens group G1. The third lens group G3 moves toward the object side while widening the distance from the second lens group G2. The fourth lens group G4 moves slightly toward the image side while widening the distance from the third lens group G3.

  In order from the object side, the first lens group G1 includes a cemented lens of a biconcave negative lens and a positive meniscus lens having a convex surface facing the object side. The second lens group G2 includes a biconvex positive lens and a convex surface facing the object side. The third lens group G3 is composed of one positive meniscus lens having a convex surface facing the object side, and a fourth lens group G4. Consists of a convex positive lens.

  The aspherical surfaces are the most object-side surface and the most image-side surface of the cemented lens of the first lens group G1, both surfaces of a single biconvex positive lens of the second lens group G2, and a positive meniscus lens of the third lens group G3. And 7 surfaces of the object-side surface of the convex positive lens of the fourth lens group G4.

  As shown in FIG. 11, the zoom lens of Example 11 includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a positive refractive power, The fourth lens group G4 has a positive refractive power, and the brightness stop S is integrally disposed in the second lens group G2. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the image side. The aperture stop S and the second lens group G2 monotonously move toward the object side while integrally reducing the distance between the first lens group G1. The third lens group G3 moves toward the object side while widening the distance from the second lens group G2. The fourth lens group G4 moves to the image side.

  In order from the object side, the first lens group G1 includes a cemented lens of a biconcave negative lens and a positive meniscus lens having a convex surface facing the object side. The second lens group G2 includes a biconvex positive lens and an aperture stop S. And a cemented lens of a positive meniscus lens having a convex surface facing the object side and a negative meniscus lens having a convex surface facing the object side, and the third lens group G3 is composed of a single positive meniscus lens having a convex surface facing the image side. The fourth lens group G4 is composed of one biconvex positive lens.

  The aspherical surfaces are the most object-side surface and the most image-side surface of the cemented lens of the first lens group G1, both surfaces of the biconvex positive lens of the single lens of the second lens group G2, the most image-side surface of the cemented lens, It is used on both surfaces of the positive meniscus lens of the third lens group G3 and on the object side surface of the biconvex positive lens of the fourth lens group G4.

  As shown in FIG. 12, the zoom lens of Example 12 includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a positive refractive power. The fourth lens group G4 has a positive refractive power, and the brightness stop S is disposed integrally with the second lens group G2 on the image side of the second lens group G2. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves along a locus convex toward the image side, and at the telephoto end is located slightly closer to the object side than the wide-angle end position. The second lens group G2 and the aperture stop S move monotonously toward the object side while reducing the distance between the first lens group G1 and the first lens group G2. The third lens group G3 moves toward the object side while widening the distance from the second lens group G2. The fourth lens group G4 moves to the image side.

  In order from the object side, the first lens group G1 includes a cemented lens of a biconcave negative lens and a positive meniscus lens having a convex surface facing the object side. The second lens group G2 includes a biconvex positive lens and a convex surface facing the object side. The third lens group G3 is composed of a negative meniscus lens having a convex surface facing the object side and a negative meniscus lens having a convex surface facing the image side, and a biconvex positive lens. The four lens group G4 is composed of one positive meniscus lens having a convex surface facing the image side.

  The aspherical surfaces are the most object-side surface and the most image-side surface of the cemented lens of the first lens group G1, both surfaces of the biconvex positive lens of the single lens of the second lens group G2, the most object-side surface of the cemented lens, It is used on both surfaces of the biconvex positive lens of the third lens group G3 and on both surfaces of the positive meniscus lens of the fourth lens group G4.

  As shown in FIG. 13, the zoom lens of Example 13 includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a positive refractive power, The fourth lens group G4 has a negative refractive power, and the aperture stop S is integrally disposed in the second lens group G2. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the image side. The aperture stop S and the second lens group G2 monotonously move toward the object side while integrally reducing the distance between the first lens group G1. The third lens group G3 moves toward the object side while widening from the intermediate state to the telephoto end while slightly reducing the distance from the second lens group G2 from the wide-angle end to the intermediate state. The fourth lens group G4 moves along a locus convex toward the object side while increasing the distance from the third lens group G3, and is located closer to the image side than the wide-angle end position at the telephoto end.

  In order from the object side, the first lens group G1 includes one biconcave negative lens, and the second lens group G2 includes a biconvex positive lens, an aperture stop S, and a positive meniscus lens having a convex surface facing the object side. And a negative meniscus lens having a convex surface facing the object side, the third lens group G3 is composed of one positive meniscus lens having a convex surface facing the object side, and the fourth lens group G4 is a convex surface facing the image side. It consists of one negative meniscus lens.

  The aspheric surfaces are both surfaces of the biconcave negative lens of the first lens group G1, both surfaces of the biconvex positive lens of the single lens of the second lens group G2, both surfaces of the positive meniscus lens of the third lens group G3, and the fourth lens group G4. 7 are used on the image side surface of the negative meniscus lens.

  As shown in FIG. 14, in the zoom lens of Example 14, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a positive refractive power, The fourth lens group G4 has a positive refractive power, and the brightness stop S is disposed integrally with the second lens group G2 on the image side of the second lens group G2. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves along a locus convex toward the image side, and is slightly closer to the image side than the wide-angle end position at the telephoto end. The second lens group G2 and the aperture stop S move monotonously toward the object side while reducing the distance between the first lens group G1 and the first lens group G2. The third lens group G3 moves while drawing a convex locus toward the object side while widening from the intermediate state to the telephoto end while slightly reducing the distance from the second lens group G2 from the wide-angle end to the intermediate state. Located on the object side from the edge position. The fourth lens group G4 moves to the image side.

  In order from the object side, the first lens group G1 includes one biconcave negative lens, and the second lens group G2 includes a biconvex positive lens, a positive meniscus lens having a convex surface on the object side, and a convex surface on the object side. The third lens group G3 is composed of a negative meniscus lens having a convex surface facing the image side and a biconvex positive lens, and the fourth lens group G4 has a convex surface facing the image side. It consists of one positive meniscus lens.

  The aspherical surfaces are both surfaces of the biconcave negative lens of the first lens group G1, both surfaces of the biconvex positive lens of the single lens of the second lens group G2, the most image side surface of the cemented lens, and the biconvex of the third lens group G3. It is used on both surfaces of the positive lens and on both surfaces of the positive meniscus lens of the fourth lens group G4.

  As shown in FIG. 15, the zoom lens of Example 15 includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a positive refractive power. The fourth lens group G4 has a positive refractive power, and the brightness stop S is disposed integrally with the second lens group G2 on the image side of the second lens group G2. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves along a locus convex toward the image side, and is slightly closer to the image side than the wide-angle end position at the telephoto end. The second lens group G2 and the aperture stop S move monotonously toward the object side while reducing the distance between the first lens group G1 and the first lens group G2. The third lens group G3 moves along a locus convex toward the object side while increasing the distance from the second lens group G2, and is located closer to the object side at the telephoto end than at the wide-angle end. The fourth lens group G4 moves toward the image side while being slightly contracted from the intermediate state to the telephoto end while increasing the distance from the third lens group G3 from the wide-angle end to the intermediate state.

  In order from the object side, the first lens group G1 includes one biconcave negative lens, and the second lens group G2 includes a biconvex positive lens, a positive meniscus lens having a convex surface on the object side, and a convex surface on the object side. The third lens group G3 is composed of a negative meniscus lens having a convex surface facing the image side and a biconvex positive lens, and the fourth lens group G4 has a convex surface facing the image side. It consists of one positive meniscus lens.

  The aspheric surfaces are both surfaces of the biconcave negative lens of the first lens group G1, both surfaces of the biconvex positive lens of the single lens of the second lens group G2, the most object side surface of the cemented lens, and the biconvex of the third lens group G3. It is used on both surfaces of the positive lens and on both surfaces of the positive meniscus lens of the fourth lens group G4.

Hereinafter, numerical data of each embodiment described above, but the symbols are outside the above, f is the focal length, F _NO is the F-number, 2 [omega is field angle, WE denotes a wide angle end, ST intermediate state, TE is The telephoto end, r ₁ , r ₂ ... Is the radius of curvature of each lens surface, d ₁ , d ₂ ... _Are the distances between the lens surfaces, n _d1 , n _d2 are the refractive index of the d-line of each lens, ν _d1 , ν _d2 ... is the Abbe number of each lens. The aspherical shape is represented by the following formula, where x is an optical axis with the light traveling direction being positive, and y is a direction orthogonal to the optical axis.

x = (y ² / r) / [1+ {1- (K + 1) (y / r) ² } ^1/2 ]
+ A ₄ y ⁴ + A ₆ y ⁶ + A ₈ y ⁸ + A ₁₀ y ¹⁰ + A ₁₂ y ¹² + A ₁₄ y ¹⁴
Where r is a paraxial radius of curvature, K is a conic coefficient, A ₄ , A ₆ , A ₈ , A ₁₀ , A ₁₂ , A ₁₄ are 4th, 6th, 8th, 10th, 12th, 14th, respectively. Is the aspheric coefficient.

Example 1
r ₁ = -20.591 (aspherical surface) d ₁ = 0.85 n _d1 = 1.74320 ν _d1 = 49.34
r ₂ = 11.203 (aspherical surface) d ₂ = 1.99
r ₃ = 22.665 d ₃ = 2.40 n _d2 = 2.00330 ν _d2 = 28.27
r ₄ = -1878.730 d ₄ = (variable)
r ₅ = ∞ (aperture) d ₅ = 0.00
r ₆ = 8.370 (aspherical surface) d ₆ = 2.80 n _d3 = 1.59201 ν _d3 = 67.02
r ₇ = -38.980 (aspherical surface) d ₇ = 0.10
r ₈ = 9.076 d ₈ = 2.40 n _d4 = 1.88300 ν _d4 = 40.76
r ₉ = 159.652 d ₉ = 0.50 n _d5 = 1.76182 ν _d5 = 26.52
r ₁₀ = 4.770 d ₁₀ = (variable)
r ₁₁ = 163.107 d ₁₁ = 2.30 n _d6 = 1.52542 ν _d6 = 55.78
r ₁₂ = -13.302 (aspherical surface) d ₁₂ = (variable)
r ₁₃ = 47.335 (aspherical surface) d ₁₃ = 0.80 n _d7 = 1.52542 ν _d7 = 55.78
r ₁₄ = 157.532 d ₁₄ = 0.50
r ₁₅ = ∞ d ₁₅ = 0.74 n _d8 = 1.54771 ν _d8 = 62.84
r ₁₆ = ∞ d ₁₆ = 0.50
r ₁₇ = ∞ d ₁₇ = 0.50 n _d9 = 1.51633 ν _d9 = 64.14
r ₁₈ = ∞ d ₁₈ = 1.00
r ₁₉ = ∞ (image plane)
Aspheric coefficient 1st surface K = -4.857
A ₄ = 1.91170 × 10 ^-5
A ₆ = -7.93990 × 10 ^-7
A ₈ = 1.25291 × 10 ^-8
A ₁₀ = 0
Second side K = -0.331
A ₄ = -4.83010 × 10 ^-5
A ₆ = -1.87391 × 10 ^-6
A ₈ = 9.14916 × 10 ^-8
A ₁₀ = -2.06253 × 10 ^-9
A ₁₂ = 1.96883 × 10 ^-11
6th surface K = -0.325
A ₄ = -1.08286 × 10 ^-4
A ₆ = 5.17066 × 10 ^-7
A ₈ = -7.59167 × 10 ^-8
A ₁₀ = 3.18869 × 10 ^-9
Surface 7 K = -18.058
A ₄ = 7.08103 × 10 ^-5
A ₆ = 5.33584 × 10 ^-7
A ₈ = -6.05038 × 10 ^-8
A ₁₀ = 3.22384 × 10 ^-9
Surface 12 K = 0.000
A ₄ = 2.25205 × 10 ^-4
A ₆ = 1.09111 × 10 ^-5
A ₈ = -1.45088 × 10 ^-6
A ₁₀ = 2.99941 × 10 ^-8
Surface 13 K = 0.000
A ₄ = -3.95988 × 10 ^-4
A ₆ = 5.73474 × 10 ^-5
A ₈ = -4.14057 × 10 ^-6
A ₁₀ = 6.74351 × 10 ^-8
Zoom data (∞)
WE ST TE
f (mm) 7.98 12.38 22.98
F _NO 1.84 2.30 3.45
2ω (°) 62.01 39.12 21.14
d ₄ 17.81 9.15 1.30
d ₁₀ 6.49 11.36 21.21
d ₁₂ 2.51 1.87 1.55.

Example 2
r ₁ = -24.369 (aspherical surface) d ₁ = 0.85 n _d1 = 1.74320 ν _d1 = 49.34
r ₂ = 9.860 (aspherical surface) d ₂ = 2.17
r ₃ = 23.496 d ₃ = 2.40 n _d2 = 2.00330 ν _d2 = 28.27
r ₄ = -235.853 d ₄ = (variable)
r ₅ = ∞ (aperture) d ₅ = 0.00
r ₆ = 7.700 (aspherical surface) d ₆ = 2.80 n _d3 = 1.59201 ν _d3 = 67.02
r ₇ = -37.265 (aspherical surface) d ₇ = 0.10
r ₈ = 9.047 d ₈ = 2.40 n _d4 = 1.88300 ν _d4 = 40.76
r ₉ = 52.604 d ₉ = 0.50 n _d5 = 1.78472 ν _d5 = 25.68
r ₁₀ = 4.574 d ₁₀ = (variable)
r ₁₁ = 171.626 d ₁₁ = 2.30 n _d6 = 1.52542 ν _d6 = 55.78
r ₁₂ = -11.651 (aspherical surface) d ₁₂ = (variable)
r ₁₃ = ∞ d ₁₃ = 0.74 n _d7 = 1.54771 ν _d7 = 62.84
r ₁₄ = ∞ d ₁₄ = 0.50
r ₁₅ = ∞ d ₁₅ = 0.50 n _d8 = 1.51633 ν _d8 = 64.14
r ₁₆ = ∞ d ₁₆ = 1.00
r ₁₇ = ∞ (image plane)
Aspheric coefficient 1st surface K = -1.139
A ₄ = 2.02421 × 10 ^-5
A ₆ = -9.60379 × 10 ^-7
A ₈ = 1.58142 × 10 ^-8
A ₁₀ = 0
Second side K = -0.491
A ₄ = -1.25226 × 10 ^-4
A ₆ = -2.13739 × 10 ^-6
A ₈ = 7.45918 × 10 ^-8
A ₁₀ = -1.10786 × 10 ^-9
A ₁₂ = 9.55589 × 10 ^-12
6th surface K = -0.367
A ₄ = -1.10084 × 10 ^-4
A ₆ = -2.26216 × 10 ^-6
A ₈ = 7.28014 × 10 ^-8
A ₁₀ = -4.77178 × 10 ^-10
Surface 7 K = -9.634
A ₄ = 9.98274 × 10 ^-5
A ₆ = -2.11753 × 10 ^-6
A ₈ = 9.22826 × 10 ^-8
A ₁₀ = -7.79379 × 10 ^-10
Surface 12 K = -1.098
A ₄ = 6.82670 × 10 ^-4
A ₆ = -3.32068 × 10 ^-5
A ₈ = 1.32590 × 10 ^-6
A ₁₀ = -2.29769 × 10 ^-8
Zoom data (∞)
WE ST TE
f (mm) 7.89 12.63 22.74
F _NO 1.84 2.36 3.54
2ω (°) 61.68 38.23 21.61
d ₄ 17.52 8.34 1.30
d ₁₀ 6.12 11.18 20.44
d ₁₂ 3.22 2.52 1.44.

Example 3
r ₁ = -32.805 (aspherical surface) d ₁ = 0.85 n _d1 = 1.74320 ν _d1 = 49.34
r ₂ = 8.821 (aspherical surface) d ₂ = 2.37
r ₃ = 21.367 d ₃ = 2.40 n _d2 = 2.00330 ν _d2 = 28.27
r ₄ = -990.027 d ₄ = (variable)
r ₅ = ∞ (aperture) d ₅ = 0.00
r ₆ = 8.138 (aspherical surface) d ₆ = 2.80 n _d3 = 1.59201 ν _d3 = 67.02
r ₇ = -49.623 (aspherical surface) d ₇ = 0.10
r ₈ = 9.644 d ₈ = 2.40 n _d4 = 1.88300 ν _d4 = 40.76
r ₉ = -398.189 d ₉ = 0.50 n _d5 = 1.76182 ν _d5 = 26.52
r ₁₀ = 4.845 d ₁₀ = (variable)
r ₁₁ = 23.104 d ₁₁ = 2.30 n _d6 = 1.52542 ν _d6 = 55.78
r ₁₂ = -25.555 (aspherical surface) d ₁₂ = (variable)
r ₁₃ = 37.552 (aspherical surface) d ₁₃ = 0.80 n _d7 = 1.52542 ν _d7 = 55.78
r ₁₄ = ∞ d ₁₄ = 0.50
r ₁₅ = ∞ d ₁₅ = 0.74 n _d8 = 1.54771 ν _d8 = 62.84
r ₁₆ = ∞ d ₁₆ = 0.50
r ₁₇ = ∞ d ₁₇ = 0.50 n _d9 = 1.51633 ν _d9 = 64.14
r ₁₈ = ∞ d ₁₈ = 0.93
r ₁₉ = ∞ (image plane)
Aspheric coefficient 1st surface K = 0.000
A ₄ = -7.23340 × 10 ^-5
A ₆ = 7.82522 × 10 ^-7
A ₈ = 1.74057 × 10 ^-8
A ₁₀ = -2.80490 × 10 ^-10
Second side K = -0.680
A ₄ = -2.17245 × 10 ^-4
A ₆ = 9.78691 × 10 ^-7
A ₈ = 2.15020 × 10 ^-8
A ₁₀ = -7.54735 × 10 ^-12
A ₁₂ = -6.96482 × 10 ^-12
6th surface K = -0.211
A ₄ = -1.08462 × 10 ^-4
A ₆ = -6.11103 × 10 ^-7
A ₈ = -4.74554 × 10 ^-8
A ₁₀ = 2.70946 × 10 ^-9
Surface 7 K = 0.000
A ₄ = 1.17441 × 10 ^-4
A ₆ = -1.80136 × 10 ^-7
A ₈ = -2.26721 × 10 ^-8
A ₁₀ = 2.61135 × 10 ^-9
Surface 12 K = 0.000
A ₄ = -4.78766 × 10 ^-5
A ₆ = 3.82653 × 10 ^-6
A ₈ = -1.68282 × 10 ^-7
A ₁₀ = 2.74886 × 10 ^-9
Surface 13 K = 0.000
A ₄ = -5.40034 × 10 ^-4
A ₆ = 1.23392 × 10 ^-5
A ₈ = -2.71717 × 10 ^-7
A ₁₀ = 3.52095 × 10 ^-9
Zoom data (∞)
WE ST TE
f (mm) 8.01 13.61 23.18
F _NO 1.84 2.41 3.45
2ω (°) 60.98 36.09 21.26
d ₄ 18.24 6.57 1.23
d ₁₀ 7.26 12.17 23.55
d ₁₂ 2.58 3.38 1.71.

Example 4
r ₁ = -32.705 (aspherical surface) d ₁ = 0.85 n _d1 = 1.74320 ν _d1 = 49.34
r ₂ = 8.879 (aspherical surface) d ₂ = 2.38
r ₃ = 21.569 d ₃ = 2.30 n _d2 = 2.00330 ν _d2 = 28.27
r ₄ = 202364.298 d ₄ = (variable)
r ₅ = ∞ (aperture) d ₅ = 0.00
r ₆ = 8.220 (aspherical surface) d ₆ = 2.80 n _d3 = 1.59201 ν _d3 = 67.02
r ₇ = -47.063 (aspherical surface) d ₇ = 0.10
r ₈ = 9.799 d ₈ = 2.40 n _d4 = 1.88300 ν _d4 = 40.76
r ₉ = -111.185 d ₉ = 0.53 n _d5 = 1.76182 ν _d5 = 26.52
r ₁₀ = 4.926 d ₁₀ = (variable)
r ₁₁ = 25.699 d ₁₁ = 2.30 n _d6 = 1.52542 ν _d6 = 55.78
r ₁₂ = -22.867 (aspherical surface) d ₁₂ = (variable)
r ₁₃ = -34.483 (aspherical surface) d ₁₃ = 0.80 n _d7 = 1.52542 ν _d7 = 55.78
r ₁₄ = -21.613 d ₁₄ = (variable)
r ₁₅ = ∞ d ₁₅ = 0.74 n _d8 = 1.54771 ν _d8 = 62.84
r ₁₆ = ∞ d ₁₆ = 0.20
r ₁₇ = ∞ d ₁₇ = 0.50 n _d9 = 1.51633 ν _d9 = 64.14
r ₁₈ = ∞ d ₁₈ = 1.00
r ₁₉ = ∞ (image plane)
Aspheric coefficient 1st surface K = 0.000
A ₄ = -3.37307 × 10 ^-5
A ₆ = -9.72817 × 10 ^-7
A ₈ = 4.31496 × 10 ^-8
A ₁₀ = -4.11460 × 10 ^-10
Second side K = -0.674
A ₄ = -1.76528 × 10 ^-4
A ₆ = -1.06503 × 10 ^-6
A ₈ = 4.02343 × 10 ^-8
A ₁₀ = 2.29184 × 10 ^-10
A ₁₂ = -1.01966 × 10 ^-11
6th surface K = -0.210
A ₄ = -1.21130 × 10 ^-4
A ₆ = -8.55663 × 10 ^-7
A ₈ = -3.16534 × 10 ^-8
A ₁₀ = 1.27827 × 10 ^-9
Surface 7 K = 0.000
A ₄ = 1.09439 × 10 ^-4
A ₆ = -8.89418 × 10 ^-7
A ₈ = 7.17937 × 10 ^-9
A ₁₀ = 8.91942 × 10 ^-10
Surface 12 K = 0.000
A ₄ = -8.69778 × 10 ^-5
A ₆ = 8.22798 × 10 ^-6
A ₈ = -3.15609 × 10 ^-7
A ₁₀ = 4.70020 × 10 ^-9
Surface 13 K = 0.000
A ₄ = -7.46044 × 10 ^-4
A ₆ = 2.71091 × 10 ^-5
A ₈ = -7.30692 × 10 ^-7
A ₁₀ = 9.34974 × 10 ^-9
Zoom data (∞)
WE ST TE
f (mm) 8.01 13.55 23.21
F _NO 1.84 2.41 3.45
2ω (°) 60.75 36.12 21.27
d ₄ 18.51 7.09 1.60
d ₁₀ 7.22 12.00 23.05
d ₁₂ 1.35 3.07 2.29
d ₁₄ 2.03 1.09 0.52.

Example 5
r ₁ = -145.383 (aspherical surface) d ₁ = 0.90 n _d1 = 1.69350 ν _d1 = 53.21
r ₂ = 8.650 d ₂ = 2.00 n _d2 = 2.00069 ν _d2 = 25.46
r ₃ = 10.651 d ₃ = (variable)
r ₄ = 12.185 (aspherical surface) d ₄ = 2.26 n _d3 = 1.74320 ν _d3 = 49.34
r ₅ = 81.448 (aspherical surface) d ₅ = 0.80
r ₆ = ∞ (aperture) d ₆ = 0.20
r ₇ = 111.218 d ₇ = 0.55 n _d4 = 1.84666 ν _d4 = 23.78
r ₈ = 8.992 d ₈ = 2.50 n _d5 = 1.88300 ν _d5 = 40.76
r ₉ = -45.340 d ₉ = (variable)
r ₁₀ = 11.124 (aspherical surface) d ₁₀ = 2.00 n _d6 = 1.69350 ν _d6 = 53.21
r ₁₁ = 21.087 (aspherical surface) d ₁₁ = (variable)
r ₁₂ = -13.435 d ₁₂ = 1.00 n _d7 = 1.68893 ν _d7 = 31.07
r ₁₃ = -21.718 (aspherical surface) d ₁₃ = (variable)
r ₁₄ = ∞ d ₁₄ = 0.74 n _d8 = 1.54771 ν _d8 = 62.84
r ₁₅ = ∞ d ₁₅ = 0.50
r ₁₆ = ∞ d ₁₆ = 0.50 n _d9 = 1.51633 ν _d9 = 64.14
r ₁₇ = ∞ d ₁₇ = 0.50
r ₁₈ = ∞ (image plane)
Aspheric coefficient 1st surface K = 0.000
A ₄ = 1.25228 × 10 ^-5
A ₆ = -1.68857 × 10 ^-7
A ₈ = 5.23426 × 10 ^-9
A ₁₀ = -1.91214 × 10 ^-11
A ₁₂ = -2.14972 × 10 ^-12
A ₁₄ = 2.50471 × 10 ^-14
4th surface K = -2.274
A ₄ = -1.31273 × 10 ^-4
A ₆ = -6.67025 × 10 ^-6
A ₈ = 3.40034 × 10 ^-8
A ₁₀ = -7.37366 × 10 ^-9
Fifth side K = 0.000
A ₄ = -2.71343 × 10 ^-4
A ₆ = -3.88226 × 10 ^-6
A ₈ = -1.41496 × 10 ^-7
A ₁₀ = -1.80000 × 10 ^-9
Surface 10 K = -2.888
A ₄ = -3.04589 × 10 ^-4
A ₆ = -1.11767 × 10 ^-5
A ₈ = -5.04355 × 10 ^-7
A ₁₀ = 0
11th surface K = 0.000
A ₄ = -7.15384 × 10 ^-4
A ₆ = -1.94625 × 10 ^-5
A ₈ = 0
A ₁₀ = 0
Surface 13 K = 0.000
A ₄ = 8.96159 × 10 ^-4
A ₆ = 5.87184 × 10 ^-6
A ₈ = -2.49866 × 10 ^-7
A ₁₀ = 0
Zoom data (∞)
WE ST TE
f (mm) 7.99 12.35 22.99
F _NO 1.86 2.14 2.84
2ω (°) 62.43 39.90 21.32
d ₃ 16.93 8.07 1.10
d ₉ 6.36 6.18 14.52
d ₁₁ 1.95 3.61 8.43
d ₁₃ 2.95 4.14 1.79.

Example 6
r ₁ = -78.142 (aspherical surface) d ₁ = 0.90 n _d1 = 1.74320 ν _d1 = 49.34
r ₂ = 8.767 d ₂ = 2.00 n _d2 = 2.00170 ν _d2 = 20.64
r ₃ = 12.214 d ₃ = (variable)
r ₄ = 11.533 (aspherical surface) d ₄ = 2.27 n _d3 = 1.74320 ν _d3 = 49.34
r ₅ = 40.855 d ₅ = 0.55 n _d4 = 1.84666 ν _d4 = 23.78
r ₆ = 7.068 d ₆ = 3.30 n _d5 = 1.88300 ν _d5 = 40.76
r ₇ = -115.072 d ₇ = 0.00
r ₈ = ∞ (aperture) d ₈ = (variable)
r ₉ = 12.459 (aspherical surface) d ₉ = 2.00 n _d6 = 1.69350 ν _d6 = 53.21
r ₁₀ = 30.922 (aspherical surface) d ₁₀ = (variable)
r ₁₁ = -14.299 d ₁₁ = 1.00 n _d7 = 1.68893 ν _d7 = 31.07
r ₁₂ = -18.793 (aspherical surface) d ₁₂ = (variable)
r ₁₃ = ∞ d ₁₃ = 0.74 n _d8 = 1.54771 ν _d8 = 62.84
r ₁₄ = ∞ d ₁₄ = 0.50
r ₁₅ = ∞ d ₁₅ = 0.50 n _d9 = 1.51633 ν _d9 = 64.14
r ₁₆ = ∞ d ₁₆ = 0.50
r ₁₇ = ∞ (image plane)
Aspheric coefficient 1st surface K = 0.000
A ₄ = 1.56906 × 10 ^-5
A ₆ = -1.29413 × 10 ^-6
A ₈ = 8.45917 × 10 ^-8
A ₁₀ = -2.66460 × 10 ^-9
A ₁₂ = 3.93437 × 10 ^-11
A ₁₄ = -2.22233 × 10 ^-13
4th surface K = 1.054
A ₄ = -1.58746 × 10 ^-4
A ₆ = -3.45221 × 10 ^-6
A ₈ = 8.56173 × 10 ^-8
A ₁₀ = -1.87648 × 10 ^-9
Surface 9 K = -1.904
A ₄ = -4.66723 × 10 ^-4
A ₆ = -1.21485 × 10 ^-5
A ₈ = -5.97308 × 10 ^-7
A ₁₀ = 0
10th surface K = 0.000
A ₄ = -7.04701 × 10 ^-4
A ₆ = -2.17479 × 10 ^-5
A ₈ = 0
A ₁₀ = 0
Surface 12 K = 0.000
A ₄ = 9.63721 × 10 ^-4
A ₆ = -3.46884 × 10 ^-6
A ₈ = 2.58483 × 10 ^-8
A ₁₀ = 0
Zoom data (∞)
WE ST TE
f (mm) 8.06 12.46 22.88
F _NO 1.86 2.17 2.99
2ω (°) 62.14 39.39 21.48
d ₃ 16.66 7.71 1.10
d ₈ 7.78 7.73 15.29
d ₁₀ 1.87 4.02 9.10
d ₁₂ 2.27 3.11 1.55.

Example 7
r ₁ = -29.732 (aspherical surface) d ₁ = 0.90 n _d1 = 1.69350 ν _d1 = 53.21
r ₂ = 14.601 d ₂ = 1.80 n _d2 = 1.83918 ν _d2 = 23.85
r ₃ = 27.894 (aspherical surface) d ₃ = (variable)
r ₄ = 12.843 (aspherical surface) d ₄ = 2.20 n _d3 = 1.74320 ν _d3 = 49.34
r ₅ = -99.138 (aspherical surface) d ₅ = 0.80
r ₆ = ∞ (aperture) d ₆ = 0.20
r ₇ = 7.183 d ₇ = 2.15 n _d4 = 1.88300 ν _d4 = 40.76
r ₈ = 29.767 d ₈ = 0.50 n _d5 = 1.80810 ν _d5 = 22.76
r ₉ = 5.037 d ₉ = (variable)
r ₁₀ = 10.779 (aspherical surface) d ₁₀ = 2.57 n _d6 = 1.69350 ν _d6 = 53.21
r ₁₁ = 42.476 (aspherical surface) d ₁₁ = (variable)
r ₁₂ = 40.000 (aspherical surface) d ₁₂ = 1.00 n _d7 = 1.52542 ν _d7 = 55.78
r ₁₃ = 30.242 d ₁₃ = 1.00
r ₁₄ = ∞ d ₁₄ = 0.74 n _d8 = 1.54771 ν _d8 = 62.84
r ₁₅ = ∞ d ₁₅ = 0.50
r ₁₆ = ∞ d ₁₆ = 0.50 n _d9 = 1.51633 ν _d9 = 64.14
r ₁₇ = ∞ d ₁₇ = 0.41
r ₁₈ = ∞ (image plane)
Aspheric coefficient 1st surface K = 0.000
A ₄ = 1.70392 × 10 ^-4
A ₆ = -2.36418 × 10 ^-6
A ₈ = 1.14962 × 10 ^-8
A ₁₀ = 3.13033 × 10 ^-10
A ₁₂ = -5.19506 × 10 ^-12
A ₁₄ = 2.48049 × 10 ^-14
Third side K = 0.000
A ₄ = 1.33513 × 10 ^-4
A ₆ = -1.87741 × 10 ^-6
A ₈ = 1.49663 × 10 ^-8
A ₁₀ = 3.63709 × 10 ^-11
4th surface K = 0.597
A ₄ = -1.74298 × 10 ^-4
A ₆ = -1.34175 × 10 ^-6
A ₈ = -8.12069 × 10 ^-8
A ₁₀ = -2.96234 × 10 ^-9
Fifth side K = 0.000
A ₄ = -7.76740 × 10 ^-5
A ₆ = -8.18520 × 10 ^-7
A ₈ = -1.51793 × 10 ^-7
A ₁₀ = -4.25649 × 10 ^-10
10th surface K = 0.000
A ₄ = -3.34112 × 10 ^-4
A ₆ = 1.72489 × 10 ^-6
A ₈ = -1.12625 × 10 ^-7
A ₁₀ = 0
11th surface K = 0.000
A ₄ = -6.82941 × 10 ^-4
A ₆ = 3.40824 × 10 ^-6
A ₈ = -5.60943 × 10 ^-8
A ₁₀ = 0
Surface 12 K = 0.000
A ₄ = -1.84764 × 10 ^-3
A ₆ = 5.24923 × 10 ^-5
A ₈ = -3.73324 × 10 ^-6
A ₁₀ = 1.00779 × 10 ^-7
Zoom data (∞)
WE ST TE
f (mm) 7.86 12.38 22.52
F _NO 1.86 2.18 3.04
2ω (°) 63.24 39.99 22.67
d ₃ 21.80 9.68 1.69
d ₉ 6.30 7.92 17.36
d ₁₁ 1.64 3.31 4.99.

Example 8
r ₁ = -20.204 (aspherical surface) d ₁ = 0.90 n _d1 = 1.49700 ν _d1 = 81.54
r ₂ = 17.545 d ₂ = 1.80 n _d2 = 1.84666 ν _d2 = 23.78
r ₃ = 23.794 (aspherical surface) d ₃ = (variable)
r ₄ = ∞ (aperture) d ₄ = 0.10 r ₅ = 18.034 (aspherical surface) d ₅ = 2.20 n _d3 = 1.69350 ν _d3 = 53.21
r ₆ = -27.012 (aspherical surface) d ₆ = 0.10
r ₇ = 6.333 d ₇ = 2.60 n _d4 = 1.88300 ν _d4 = 40.76
r ₈ = 12.298 d ₈ = 0.60 n _d5 = 1.92286 ν _d5 = 20.88
r ₉ = 4.561 d ₉ = (variable)
r ₁₀ = 53.796 d ₁₀ = 2.80 n _d6 = 1.74320 ν _d6 = 49.34
r ₁₁ = -14.000 (aspherical surface) d ₁₁ = (variable)
r ₁₂ = -24.948 (aspherical surface) d ₁₂ = 1.00 n _d7 = 1.52542 ν _d7 = 55.78
r ₁₃ = -14.904 d ₁₃ = (variable)
r ₁₄ = ∞ d ₁₄ = 0.74 n _d8 = 1.54771 ν _d8 = 62.84
r ₁₅ = ∞ d ₁₅ = 0.50
r ₁₆ = ∞ d ₁₆ = 0.50 n _d9 = 1.51633 ν _d9 = 64.14
r ₁₇ = ∞ d ₁₇ = 0.63
r ₁₈ = ∞ (image plane)
Aspheric coefficient 1st surface K = 0.000
A ₄ = 4.98101 × 10 ^-5
A ₆ = 2.62991 × 10 ^-7
A ₈ = -1.54568 × 10 ^-8
A ₁₀ = 5.46523 × 10 ^-10
A ₁₂ = -8.17649 × 10 ^-12
A ₁₄ = 3.64148 × 10 ^-14
Third side K = 0.000
A ₄ = -1.34508 × 10 ^-5
A ₆ = 8.32834 × 10 ^-8
A ₈ = 2.05078 × 10 ^-8
A ₁₀ = -3.59245 × 10 ^-10
Fifth side K = -2.484
A ₄ = -4.56019 × 10 ^-5
A ₆ = 1.56225 × 10 ^-7
A ₈ = -5.92118 × 10 ^-8
A ₁₀ = -5.94787 × 10 ^-11
6th surface K = -1.006
A ₄ = -7.09011 × 10 ^-7
A ₆ = -5.19547 × 10 ^-7
A ₈ = -3.21483 × 10 ^-8
A ₁₀ = -3.47781 × 10 ^-10
11th surface K = -3.068
A ₄ = -1.15031 × 10 ^-4
A ₆ = -1.41621 × 10 ^-6
A ₈ = 2.96767 × 10 ^-8
A ₁₀ = 0
Surface 12 K = 0.000
A ₄ = -1.17795 × 10 ^-3
A ₆ = 1.48055 × 10 ^-5
A ₈ = -1.81960 × 10 ^-8
A ₁₀ = 0
Zoom data (∞)
WE ST TE
f (mm) 8.17 12.51 23.49
F _NO 1.86 2.25 3.35
2ω (°) 61.31 38.70 20.79
d ₃ 18.23 9.18 2.05
d ₉ 5.72 9.27 19.64
d ₁₁ 1.47 2.41 2.19
d ₁₃ 1.20 0.54 0.30.

Example 9
r ₁ = -28.866 (aspherical surface) d ₁ = 0.90 n _d1 = 1.58313 ν _d1 = 59.38
r ₂ = 12.613 d ₂ = 1.80 n _d2 = 1.83918 ν _d2 = 23.85
r ₃ = 17.351 (aspherical surface) d ₃ = (variable)
r ₄ = 10.328 (aspherical surface) d ₄ = 2.14 n _d3 = 1.69350 ν _d3 = 53.21
r ₅ = -125.640 (aspherical surface) d ₅ = 0.20
r ₆ = 7.249 d ₆ = 2.60 n _d4 = 1.88300 ν _d4 = 40.76
r ₇ = -63.997 d ₇ = 0.40 n _d5 = 1.78472 ν _d5 = 25.68
r ₈ = 4.607 d ₈ = 1.50
r ₉ = ∞ (aperture) d ₉ = (variable)
r ₁₀ = 10.095 (aspherical surface) d ₁₀ = 2.20 n _d6 = 1.74320 ν _d6 = 49.34
r ₁₁ = 18.794 (aspherical surface) d ₁₁ = (variable)
r ₁₂ = 33.259 (aspherical surface) d ₁₂ = 1.00 n _d7 = 1.52542 ν _d7 = 55.78
r ₁₃ = -645.512 d ₁₃ = 1.14
r ₁₄ = ∞ d ₁₄ = 0.74 n _d8 = 1.54771 ν _d8 = 62.84
r ₁₅ = ∞ d ₁₅ = 0.50
r ₁₆ = ∞ d ₁₆ = 0.50 n _d9 = 1.51633 ν _d9 = 64.14
r ₁₇ = ∞ d ₁₇ = 0.46
r ₁₈ = ∞ (image plane)
Aspheric coefficient 1st surface K = 0.000
A ₄ = 6.38764 × 10 ^-5
A ₆ = -1.09687 × 10 ^-6
A ₈ = 2.22426 × 10 ^-8
A ₁₀ = 1.99264 × 10 ^-11
A ₁₂ = -2.98978 × 10 ^-12
A ₁₄ = 1.81600 × 10 ^-14
Third side K = 0.000
A ₄ = 2.14506 × 10 ^-5
A ₆ = -4.03380 × 10 ^-7
A ₈ = 2.18349 × 10 ^-8
A ₁₀ = 5.77518 × 10 ^-12
4th surface K = -0.161
A ₄ = -1.43882 × 10 ^-4
A ₆ = -1.09831 × 10 ^-7
A ₈ = -8.65978 × 10 ^-9
A ₁₀ = -3.29195 × 10 ^-10
Fifth side K = 0.000
A ₄ = -2.18434 × 10 ^-5
A ₆ = 2.23702 × 10 ^-7
A ₈ = -9.89591 × 10 ^-9
A ₁₀ = -1.54656 × 10 ^-10
10th surface K = 0.000
A ₄ = -5.79354 × 10 ^-4
A ₆ = 1.20789 × 10 ^-5
A ₈ = -2.73123 × 10 ^-7
A ₁₀ = 0
11th surface K = 0.000
A ₄ = -1.07181 × 10 ^-3
A ₆ = 2.06212 × 10 ^-5
A ₈ = -3.85314 × 10 ^-7
A ₁₀ = 0
Surface 12 K = 0.000
A ₄ = -1.57377 × 10 ^-3
A ₆ = 0
A ₈ = 0
A ₁₀ = 0
Zoom data (∞)
WE ST TE
f (mm) 7.99 12.24 22.75
F _NO 1.86 2.29 3.46
2ω (°) 62.67 40.39 22.11
d ₃ 17.00 8.17 1.43
d ₉ 3.90 5.09 13.29
d ₁₁ 1.51 3.27 5.31.

Example 10
r ₁ = -45.206 (aspherical surface) d ₁ = 0.90 n _d1 = 1.69350 ν _d1 = 53.21
r ₂ = 11.291 d ₂ = 1.80 n _d2 = 1.84666 ν _d2 = 23.78
r ₃ = 17.553 (aspherical surface) d ₃ = (variable)
r ₄ = ∞ (aperture) d ₄ = 0.10 r ₅ = 9.783 (aspheric surface) d ₅ = 2.26 n _d3 = 1.74320 ν _d3 = 49.34
r ₆ = -107.620 (aspherical surface) d ₆ = 0.10
r ₇ = 6.333 d ₇ = 2.00 n _d4 = 1.72916 ν _d4 = 54.68
r ₈ = 9.228 d ₈ = 0.60 n _d5 = 2.00170 ν _d5 = 20.64
r ₉ = 4.744 d ₉ = (variable)
r ₁₀ = 14.018 (aspherical surface) d ₁₀ = 2.72 n _d6 = 1.69350 ν _d6 = 53.21
r ₁₁ = 260.132 (aspherical surface) d ₁₁ = (variable)
r ₁₂ = 130.344 (aspherical surface) d ₁₂ = 1.00 n _d7 = 1.52542 ν _d7 = 55.78
r ₁₃ = ∞ d ₁₃ = (variable)
r ₁₄ = ∞ d ₁₄ = 0.74 n _d8 = 1.54771 ν _d8 = 62.84
r ₁₅ = ∞ d ₁₅ = 0.50
r ₁₆ = ∞ d ₁₆ = 0.50 n _d9 = 1.51633 ν _d9 = 64.14
r ₁₇ = ∞ d ₁₇ = 0.90
r ₁₈ = ∞ (image plane)
Aspheric coefficient 1st surface K = 0.000
A ₄ = 1.90374 × 10 ^-6
A ₆ = -3.84263 × 10 ^-7
A ₈ = 8.63693 × 10 ^-9
A ₁₀ = 6.67354 × 10 ^-12
A ₁₂ = -1.53332 × 10 ^-12
A ₁₄ = 1.13376 × 10 ^-14
Third side K = 0.000
A ₄ = -2.63248 × 10 ^-5
A ₆ = 2.90936 × 10 ^-7
A ₈ = -1.20811 × 10 ^-8
A ₁₀ = 1.85370 × 10 ^-10
Fifth side K = -0.263
A ₄ = -5.86359 × 10 ^-5
A ₆ = 2.39004 × 10 ^-7
A ₈ = 2.34845 × 10 ^-8
A ₁₀ = 5.34915 × 10 ^-10
6th surface K = -234.189
A ₄ = 2.88968 × 10 ^-5
A ₆ = 1.01712 × 10 ^-6
A ₈ = 9.63087 × 10 ^-9
A ₁₀ = 7.64550 × 10 ^-10
10th surface K = -6.835
A ₄ = 1.00639 × 10 ^-6
A ₆ = -4.88584 × 10 ^-6
A ₈ = 0
A ₁₀ = 0
11th surface K = 0.000
A ₄ = -4.99152 × 10 ^-4
A ₆ = -9.09044 × 10 ^-7
A ₈ = 0
A ₁₀ = 0
Surface 12 K = 0.000
A ₄ = -1.55873 × 10 ^-3
A ₆ = 5.84821 × 10 ^-6
A ₈ = 0
A ₁₀ = 0
Zoom data (∞)
WE ST TE
f (mm) 7.87 12.54 22.67
F _NO 1.86 2.14 2.93
2ω (°) 63.07 38.84 21.80
d ₃ 19.50 8.63 1.90
d ₉ 5.74 6.07 14.93
d ₁₁ 2.05 4.80 8.03
d ₁₃ 0.48 0.41 0.29.

Example 11
r ₁ = -13.852 (aspherical surface) d ₁ = 0.90 n _d1 = 1.49700 ν _d1 = 81.54
r ₂ = 24.684 d ₂ = 1.59 n _d2 = 1.83918 ν _d2 = 23.85
r ₃ = 43.897 (aspherical surface) d ₃ = (variable)
r ₄ = 10.521 (aspherical surface) d ₄ = 1.82 n _d3 = 1.69350 ν _d3 = 53.21
r ₅ = -77.251 (aspherical surface) d ₅ = 0.80
r ₆ = ∞ (aperture) d ₆ = 0.00
r ₇ = 6.907 d ₇ = 2.53 n _d4 = 1.88300 ν _d4 = 40.76
r ₈ = 87.359 d ₈ = 0.59 n _d5 = 1.83918 ν _d5 = 23.85
r ₉ = 4.354 (aspherical surface) d ₉ = (variable)
r ₁₀ = -30.574 (aspherical surface) d ₁₀ = 1.99 n _d6 = 1.80610 ν _d6 = 40.92
r ₁₁ = -12.104 (aspherical surface) d ₁₁ = (variable)
r ₁₂ = 40.000 (aspherical surface) d ₁₂ = 0.80 n _d7 = 1.52542 ν _d7 = 55.78
r ₁₃ = -73.398 d ₁₃ = (variable)
r ₁₄ = ∞ d ₁₄ = 0.74 n _d8 = 1.54771 ν _d8 = 62.84
r ₁₅ = ∞ d ₁₅ = 0.50
r ₁₆ = ∞ d ₁₆ = 0.50 n _d9 = 1.51633 ν _d9 = 64.14
r ₁₇ = ∞ d ₁₇ = 0.51
r ₁₈ = ∞ (image plane)
Aspheric coefficient 1st surface K = 0.000
A ₄ = 4.06059 × 10 ^-4
A ₆ = -6.07979 × 10 ^-6
A ₈ = 5.43296 × 10 ^-8
A ₁₀ = 3.25528 × 10 ^-11
A ₁₂ = -2.48489 × 10 ^-12
A ₁₄ = -2.01707 × 10 ^-15
Third side K = 0.000
A ₄ = 1.68867 × 10 ^-4
A ₆ = -1.12760 × 10 ^-6
A ₈ = -1.24654 × 10 ^-7
A ₁₀ = 4.77759 × 10 ^-9
A ₁₂ = -6.82004 × 10 ^-11
A ₁₄ = 3.36755 × 10 ^-13
4th surface K = 0.172
A ₄ = -1.43531 × 10 ^-4
A ₆ = 2.42963 × 10 ^-7
A ₈ = -8.81758 × 10 ^-8
A ₁₀ = 2.81587 × 10 ^-9
Fifth side K = 0.000
A ₄ = -2.60495 × 10 ^-5
A ₆ = 7.62112 × 10 ^-7
A ₈ = -2.59097 × 10 ^-9
A ₁₀ = 1.04283 × 10 ^-9
Surface 9 K = 0.000
A ₄ = 2.21869 × 10 ^-4
A ₆ = -5.83726 × 10 ^-6
A ₈ = 2.76274 × 10 ^-7
A ₁₀ = -1.82983 × 10 ^-8
10th surface K = 0.000
A ₄ = -5.33927 × 10 ^-4
A ₆ = 1.39916 × 10 ^-5
A ₈ = -1.37267 × 10 ^-7
A ₁₀ = 4.11809 × 10 ^-9
11th surface K = 0.000
A ₄ = -5.20824 × 10 ^-4
A ₆ = 1.11823 × 10 ^-5
A ₈ = -1.36807 × 10 ^-7
A ₁₀ = 3.68016 × 10 ^-9
Surface 12 K = 0.000
A ₄ = -1.22480 × 10 ^-3
A ₆ = 4.02065 × 10 ^-5
A ₈ = -1.24733 × 10 ^-6
A ₁₀ = 1.99247 × 10 ^-8
Zoom data (∞)
WE ST TE
f (mm) 8.10 10.89 23.55
F _NO 1.86 2.11 3.21
2ω (°) 61.86 44.92 21.09
d ₃ 19.16 11.95 0.50
d ₉ 3.97 4.97 12.74
d ₁₁ 2.16 4.03 6.90
d ₁₃ 1.80 0.81 0.19.

Example 12
r ₁ = -18.164 (aspherical surface) d ₁ = 0.90 n _d1 = 1.51633 ν _d1 = 64.14
r ₂ = 13.285 d ₂ = 1.80 n _d2 = 1.83918 ν _d2 = 23.85
r ₃ = 17.066 (aspherical surface) d ₃ = (variable)
r ₄ = 13.962 (aspherical surface) d ₄ = 2.20 n _d3 = 1.74320 ν _d3 = 49.34
r ₅ = -25.345 (aspherical surface) d ₅ = 0.10
r ₆ = 6.022 (aspherical surface) d ₆ = 2.90 n _d4 = 1.80610 ν _d4 = 40.92
r ₇ = 119.085 d ₇ = 0.50 n _d5 = 2.00069 ν _d5 = 25.46
r ₈ = 4.353 d ₈ = 1.72
r ₉ = ∞ (aperture) d ₉ = (variable)
r ₁₀ = -8.900 d ₁₀ = 2.20 n _d6 = 1.92286 ν _d6 = 18.90
r ₁₁ = -12.685 d ₁₁ = 2.20
r ₁₂ = 64.569 (aspherical surface) d ₁₂ = 2.20 n _d7 = 1.80610 ν _d7 = 40.92
r ₁₃ = -13.461 (aspherical surface) d ₁₃ = (variable)
r ₁₄ = -11.384 (aspherical surface) d ₁₄ = 1.00 n _d8 = 1.52542 ν _d8 = 55.78
r ₁₅ = -6.418 (aspherical surface) d ₁₅ = (variable)
r ₁₆ = ∞ d ₁₆ = 0.74 n _d9 = 1.54771 ν _d9 = 62.84
r ₁₇ = ∞ d ₁₇ = 0.50
r ₁₈ = ∞ d ₁₈ = 0.50 n _d10 = 1.51633 ν _d10 = 64.14
r ₁₉ = ∞ d ₁₉ = 0.46
r ₂₀ = ∞ (image plane)
Aspheric coefficient 1st surface K = -0.690
A ₄ = 1.00171 × 10 ^-4
A ₆ = -1.63342 × 10 ^-7
A ₈ = 0.000
A ₁₀ = 2.47553 × 10 ^-12
Third side K = -2.051
A ₄ = 8.63337 × 10 ^-5
A ₆ = -3.14892 × 10 ^-8
A ₈ = 7.47008 × 10 ^-9
A ₁₀ = 0.000
4th surface K = -0.478
A ₄ = -1.21096 × 10 ^-4
A ₆ = 2.15656 × 10 ^-6
A ₈ = -1.23897 × 10 ^-7
A ₁₀ = 1.80977 × 10 ^-9
Fifth side K = -8.737
A ₄ = -3.31436 × 10 ^-5
A ₆ = -1.24138 × 10 ^-6
A ₈ = -6.21293 × 10 ^-9
A ₁₀ = 5.65326 × 10 ^-10
6th surface K = 0.224
A ₄ = -2.71845 × 10 ^-5
A ₆ = -6.16672 × 10 ^-6
A ₈ = 1.14404 × 10 ^-7
A ₁₀ = -6.55772 × 10 ^-9
Surface 12 K = -511.997
A ₄ = -1.35640 × 10 ^-4
A ₆ = -9.45635 × 10 ^-6
A ₈ = -1.55393 × 10 ^-7
A ₁₀ = 0
13th surface K = 0.910
A ₄ = -1.71590 × 10 ^-4
A ₆ = -7.55572 × 10 ^-6
A ₈ = -1.11729 × 10 ^-8
A ₁₀ = -1.29134 × 10 ^-9
Surface 14 K = -0.773
A ₄ = -1.36202 × 10 ^-3
A ₆ = 7.62379 × 10 ^-5
A ₈ = 0
A ₁₀ = 0
15th face K = 0.000
A ₄ = 0.000
A ₆ = 7.95903 × 10 ^-5
A ₈ = 1.49209 × 10 ^-7
A ₁₀ = 0
Zoom data (∞)
WE ST TE
f (mm) 7.33 12.42 21.06
F _NO 1.86 2.57 3.86
2ω (°) 66.51 38.99 23.65
d ₃ 19.41 10.28 5.74
d ₉ 2.74 5.59 14.38
d ₁₃ 1.12 4.30 5.22
d ₁₅ 2.44 1.20 0.49.

Example 13
r ₁ = -24.536 (aspherical surface) d ₁ = 0.90 n _d1 = 1.43875 ν _d1 = 94.93
r ₂ = 19.004 (aspherical surface) d ₂ = (variable)
r ₃ = 10.959 (aspherical surface) d ₃ = 2.40 n _d2 = 1.69350 ν _d2 = 53.21
r ₄ = -86.829 (aspherical surface) d ₄ = 0.80
r ₅ = ∞ (aperture) d ₅ = 0.20 r ₆ = 7.563 d ₆ = 2.00 n _d3 = 1.81600 ν _d3 = 46.62
r ₇ = 11.746 d ₇ = 0.55 n _d4 = 1.92286 ν _d4 = 20.88
r ₈ = 5.783 d ₈ = (variable) r ₉ = 8.932 (aspherical surface) d ₉ = 2.20 n _d5 = 1.59201 ν _d5 = 67.02
r ₁₀ = 28.850 (aspherical surface) d ₁₀ = (variable)
r ₁₁ = -16.006 d ₁₁ = 1.00 n _d6 = 1.68893 ν _d6 = 31.07
r ₁₂ = -19.735 (aspherical surface) d ₁₂ = (variable)
r ₁₃ = ∞ d ₁₃ = 0.74 n _d7 = 1.54771 ν _d7 = 62.84
r ₁₄ = ∞ d ₁₄ = 0.50
r ₁₅ = ∞ d ₁₅ = 0.50 n _d8 = 1.51633 ν _d8 = 64.14
r ₁₆ = ∞ d ₁₆ = 0.50
r ₁₇ = ∞ (image plane) aspherical coefficient first surface K = 0.000
A ₄ = 3.31292 × 10 ^-4
A ₆ = -1.13962 × 10 ^-5
A ₈ = 2.47541 × 10 ^-7
A ₁₀ = -3.22394 × 10 ^-9
A ₁₂ = 2.47078 × 10 ^-11
A ₁₄ = -8.24959 × 10 ^-14
Second side K = 0.936
A ₄ = 2.51032 × 10 ^-4
A ₆ = -7.12570 × 10 ^-6
A ₈ = 7.42959 × 10 ^-8
A ₁₀ = 0
Third side K = -0.469
A ₄ = -8.90377 × 10 ^-5
A ₆ = -2.70516 × 10 ^-6
A ₈ = 1.34920 × 10 ^-7
A ₁₀ = -6.48691 × 10 ^-9
4th surface K = 0.000
A ₄ = -4.79022 × 10 ^-5
A ₆ = -2.20902 × 10 ^-6
A ₈ = 5.88068 × 10 ^-8
A ₁₀ = -4.52956 × 10 ^-9
Surface 9 K = -0.354
A ₄ = -1.20596 × 10 ^-4
A ₆ = -4.73292 × 10 ^-6
A ₈ = -2.19357 × 10 ^-7
A ₁₀ = 0
10th surface K = 0.000
A ₄ = -2.02080 × 10 ^-4
A ₆ = -1.42932 × 10 ^-5
A ₈ = 0
A ₁₀ = 0
Surface 12 K = 0.000
A ₄ = 1.30109 × 10 ^-3
A ₆ = -2.61566 × 10 ^-5
A ₈ = 1.01606 × 10 ^-6
A ₁₀ = 0
Zoom data (∞)
WE ST TE
f (mm) 8.04 11.69 22.91
F _NO 1.79 1.99 2.75
2ω (°) 62.15 41.58 21.63
d ₂ 23.22 11.29 0.40
d ₈ 5.20 4.91 12.25
d ₁₀ 1.71 2.91 6.99
d ₁₂ 1.58 2.27 0.76.

Example 14
r ₁ = -28.621 (aspherical surface) d ₁ = 0.90 n _d1 = 1.43875 ν _d1 = 94.93
r ₂ = 13.270 (aspherical surface) d ₂ = (variable)
r ₃ = 18.910 (aspherical surface) d ₃ = 1.83 n _d2 = 1.76802 ν _d2 = 49.24
r ₄ = -52.548 (aspherical surface) d ₄ = 0.10
r ₅ = 7.084 d ₅ = 2.90 n _d3 = 1.88300 ν _d3 = 40.76
r ₆ = 27.980 d ₆ = 0.55 n _d4 = 1.83918 ν _d4 = 23.85
r ₇ = 5.338 (aspherical surface) d ₇ = 1.72
r ₈ = ∞ (aperture) d ₈ = (variable)
r ₉ = -7.790 d ₉ = 0.80 n _d5 = 1.92286 ν _d5 = 18.90
r ₁₀ = -11.396 d ₁₀ = 0.15
r ₁₁ = 60.657 (aspherical surface) d ₁₁ = 2.34 n _d6 = 1.76802 ν _d6 = 49.24
r ₁₂ = -11.972 (aspherical surface) d ₁₂ = (variable)
r ₁₃ = -26.874 (aspherical surface) d ₁₃ = 1.00 n _d7 = 1.69350 ν _d7 = 53.20
r ₁₄ = -17.612 (aspherical surface) d ₁₄ = (variable)
r ₁₅ = ∞ d ₁₅ = 0.74 n _d8 = 1.54771 ν _d8 = 62.84
r ₁₆ = ∞ d ₁₆ = 0.50
r ₁₇ = ∞ d ₁₇ = 0.50 n _d9 = 1.51633 ν _d9 = 64.14
r ₁₈ = ∞ d ₁₈ = 0.30
r ₁₉ = ∞ (image plane)
Aspheric coefficient 1st surface K = -0.134
A ₄ = 2.47196 × 10 ^-7
A ₆ = 2.34297 × 10 ^-7
A ₈ = 0.000
A ₁₀ = 0.000
Second side K = -1.454
A ₄ = 1.35646 × 10 ^-5
A ₆ = -1.44746 × 10 ^-7
A ₈ = 6.88829 × 10 ^-9
A ₁₀ = 0.000
Third side K = -0.093
A ₄ = 3.65504 × 10 ^-5
A ₆ = -1.10311 × 10 ^-7
A ₈ = -4.25458 × 10 ^-8
A ₁₀ = 2.18338 × 10 ^-10
4th surface K = -18.402
A ₄ = 3.23935 × 10 ^-5
A ₆ = -6.55955 × 10 ^-7
A ₈ = -3.93067 × 10 ^-8
A ₁₀ = 4.20213 × 10 ^-10
Surface 7 K = 0.004
A ₄ = 1.46877 × 10 ^-4
A ₆ = 8.79444 × 10 ^-6
A ₈ = 1.86813 × 10 ^-7
A ₁₀ = 8.06203 × 10 ^-9
11th surface K = -12.098
A ₄ = -1.37660 × 10 ^-4
A ₆ = 1.15212 × 10 ^-6
A ₈ = -2.15963 × 10 ^-7
A ₁₀ = 0
Surface 12 K = -0.296
A ₄ = -5.40491 × 10 ^-5
A ₆ = -2.16122 × 10 ^-6
A ₈ = -3.79109 × 10 ^-8
A ₁₀ = -2.42168 × 10 ^-9
Surface 13 K = -5.302
A ₄ = -3.55522 × 10 ^-4
A ₆ = 2.30162 × 10 ^-5
A ₈ = 0
A ₁₀ = 0
14th face K = 0.000
A ₄ = 0.000
A ₆ = 2.63358 × 10 ^-5
A ₈ = 1.38995 × 10 ^-8
A ₁₀ = 0
Zoom data (∞)
WE ST TE
f (mm) 8.14 14.00 23.45
F _NO 1.86 2.31 3.68
2ω (°) 60.86 35.29 21.39
d ₂ 20.49 6.87 5.23
d ₈ 4.12 3.63 17.92
d ₁₂ 1.11 7.40 5.08
d ₁₄ 3.67 1.80 0.28.

Example 15
r ₁ = -22.016 (aspherical surface) d ₁ = 0.90 n _d1 = 1.43875 ν _d1 = 94.93
r ₂ = 15.461 (aspherical surface) d ₂ = (variable)
r ₃ = 14.701 (aspherical surface) d ₃ = 2.06 n _d2 = 1.74320 ν _d2 = 49.34
r ₄ = -32.999 (aspherical surface) d ₄ = 0.10
r ₅ = 6.405 (aspherical surface) d ₅ = 2.90 n _d3 = 1.80610 ν _d3 = 40.92
r ₆ = 33.244 d ₆ = 0.50 n _d4 = 2.00069 ν _d4 = 25.46
r ₇ = 4.856 d ₇ = 1.72
r ₈ = ∞ (aperture) d ₈ = (variable)
r ₉ = -8.940 d ₉ = 0.80 n _d5 = 1.92286 ν _d5 = 18.90
r ₁₀ = -16.611 d ₁₀ = 0.18
r ₁₁ = 45.839 (aspherical surface) d ₁₁ = 2.55 n _d6 = 1.80610 ν _d6 = 40.92
r ₁₂ = -11.009 (aspherical surface) d ₁₂ = (variable)
r ₁₃ = -10.879 (aspherical surface) d ₁₃ = 1.00 n _d7 = 1.52542 ν _d7 = 55.78
r ₁₄ = -7.731 (aspherical surface) d ₁₄ = (variable)
r ₁₅ = ∞ d ₁₅ = 0.74 n _d8 = 1.54771 ν _d8 = 62.84
r ₁₆ = ∞ d ₁₆ = 0.50
r ₁₇ = ∞ d ₁₇ = 0.50 n _d9 = 1.51633 ν _d9 = 64.14
r ₁₈ = ∞ d ₁₈ = 0.30
r ₁₉ = ∞ (image plane)
Aspheric coefficient 1st surface K = -0.519
A ₄ = 3.69695 × 10 ^-5
A ₆ = 5.65774 × 10 ^-8
A ₈ = 0.000
A ₁₀ = 3.73887 × 10 ^-12
Second side K = -2.161
A ₄ = 4.21993 × 10 ^-5
A ₆ = -1.75597 × 10 ^-7
A ₈ = 8.97310 × 10 ^-9
A ₁₀ = 0.000
Third side K = -0.175
A ₄ = -9.06679 × 10 ^-6
A ₆ = -3.53110 × 10 ^-7
A ₈ = -2.44657 × 10 ^-8
A ₁₀ = 2.47234 × 10 ^-10
4th surface K = -17.775
A ₄ = -2.80828 × 10 ^-5
A ₆ = -1.49749 × 10 ^-7
A ₈ = -1.08247 × 10 ^-8
A ₁₀ = 1.49523 × 10 ^-10
Fifth side K = 0.037
A ₄ = -3.97693 × 10 ^-5
A ₆ = -1.02246 × 10 ^-6
A ₈ = -1.04292 × 10 ^-9
A ₁₀ = -2.35540 × 10 ^-13
11th surface K = -11.838
A ₄ = -1.64575 × 10 ^-4
A ₆ = -3.82233 × 10 ^-6
A ₈ = -2.40636 × 10 ^-7
A ₁₀ = 0
Surface 12 K = -0.837
A ₄ = -6.41167 × 10 ^-5
A ₆ = -6.74867 × 10 ^-6
A ₈ = -4.23546 × 10 ^-8
A ₁₀ = -2.74519 × 10 ^-9
Surface 13 K = -2.908
A ₄ = -1.08544 × 10 ^-3
A ₆ = 4.99868 × 10 ^-5
A ₈ = 0
A ₁₀ = 0
14th face K = 0.000
A ₄ = 0.000
A ₆ = 4.25126 × 10 ^-5
A ₈ = 1.52833 × 10 ^-7
A ₁₀ = 0
Zoom data (∞)
WE ST TE
f (mm) 8.14 13.82 23.46
F _NO 1.85 2.47 3.85
2ω (°) 60.81 35.74 21.43
d ₂ 20.70 9.76 6.47
d ₈ 3.54 6.20 17.38
d ₁₂ 1.23 5.56 4.71
d ₁₄ 3.38 1.41 0.16.

  Aberration diagrams at the time of focusing on an object point at infinity in Examples 1 to 15 are shown in FIGS. In these aberration diagrams, (a) is the wide angle end, (b) is the intermediate state, (c) is the spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration (CC) at the telephoto end. ). In each figure, “ω” indicates a half angle of view (°).

  Next, the values of conditional expressions (1) to (14) in each of the above examples are shown below.

Example 1 2 3 4 5 6 7 8
Conditional expression (1) 20.38 20.10 21.46 21.11 19.84 19.81 21.31 18.72
Conditional expression (2) 20.38 20.10 21.46 21.11 19.84 19.81 21.31 18.72
Conditional expression (3) 0.35 0.36 0.35 0.36 0.26 0.26 0.28 0.27
Conditional expression (4) 2.05 1.71 2.09 1.81 1.53 1.49 1.54 1.72
Conditional expression (5) 1.76 1.75 1.88 1.86 1.61 1.61 1.83 1.69
Conditional expression (6) 1.40 1.43 1.44 1.40 1.11 1.10 1.55 1.62
Conditional expression (7) 0.34 0.35 0.32 0.34 0.34 0.34 0.30 0.28
Conditional expression (8) 0.48 0.48 0.47 0.48 0.47 0.48 0.46 0.48
Conditional expression (9) 1.07 1.06 1.07 1.11 0.97 0.98 0.94 0.86
Conditional expression (10) 0.81 0.78 0.91 0.90 0.79 0.97 0.80 0.70
Conditional expression (11) 0.68 0.68 0.70 0.70 0.81 0.86 0.66 0.64
Conditional expression (12) 2.88 2.88 2.89 2.90 2.88 2.84 2.87 2.88
Conditional expression (13) 62.01 61.68 60.98 60.75 62.43 62.14 63.24 61.31
Conditional expression (14) 2.74 2.86 2.51 2.56 2.66 2.14 3.46 3.21

Example 9 10 11 12 13 14 15
Conditional expression (1) 17.91 19.79 18.48 21.63 19.60 19.97 19.85
Conditional expression (2) 17.91 19.79 18.48 21.69 19.60 19.97 19.85
Conditional expression (3) 0.27 0.27 0.28 0.28 0.28 0.27 0.27
Conditional expression (4) 1.41 1.70 1.36 1.76 1.25 1.30 1.35
Conditional expression (5) 1.58 1.70 1.60 1.71 1.80 1.69 1.68
Conditional expression (6) 1.38 1.36 1.60 1.36 1.68 1.36 1.36
Conditional expression (7) 0.32 0.32 0.31 0.33 0.31 0.32 0.33
Conditional expression (8) 0.47 0.47 0.48 0.43 0.49 0.48 0.48
Conditional expression (9) 0.89 0.95 0.89 0.91 0.99 0.98 0.99
Conditional expression (10) 0.68 0.73 0.49 0.61 0.65 0.72 0.65
Conditional expression (11) 0.59 0.72 0.64 0.42 0.75 0.48 0.44
Conditional expression (12) 2.85 2.88 2.91 2.87 2.85 2.88 2.88
Conditional expression (13) 62.67 63.07 61.86 66.51 62.15 60.86 60.81
Conditional expression (14) 3.15 3.41 4.83 4.34 4.47 3.50 3.94
.

  In these embodiments, the zoom ratio is as large as about 3 times, the angle of view at the wide angle end is as wide as about 60 °, and the F value at the wide angle end is as bright as about 1.8. A zoom lens that has good optical performance at a shooting distance and can be retracted compactly is realized.

  In each embodiment, the farthest focus state is a focus on an infinite object. Except for the twelfth embodiment, the entire length becomes longest when the object at the wide-angle end infinity is in focus. Note that the focusing operation to a short distance may be performed by one or both of the third lens group G3 and the fourth lens group G4.

  The aperture stop S of each embodiment may have a variable aperture size for brightness adjustment, and the aperture size of the aperture may be fixed, and the light amount may be adjusted by inserting / removing a filter to reduce the light amount at other locations. It may be.

  The aperture stop S in each embodiment is a circle centered on the optical axis when opened, and the radius of the opening is as follows.

Example Radius of opening (mm)
1 4.67
2 4.63
3 4.67
4 4.85
5 4.33
6 3.97
7 4.00
8 3.85
9 2.49
10 4.22
11 3.78
12 2.25
13 4.17
14 2.82
15 2.61.

  By the way, when the zoom lens of the present invention is used, image distortion is digitally corrected electrically. The basic concept for digitally correcting image distortion will be described below.

For example, as shown in FIG. 31, the magnification on the circumference (image height) of the radius R inscribed in the long side of the effective imaging surface around the intersection of the optical axis and the imaging surface is fixed, and this circumference is The standard for correction. Then, correction is performed by moving each point on the circumference (image height) of any other radius r (ω) in a substantially radial direction and concentrically so as to have the radius r ′ (ω). To do. For example, in FIG. 31, a point P ₁ on the circumference of an arbitrary radius r ₁ (ω) located inside the circle of radius R is a radius r ₁ ′ (ω) circle to be corrected toward the center of the circle. Move to point P ₂ on the circumference. A point Q ₁ on the circumference of an arbitrary radius r ₂ (ω) located outside the circle of radius R is a radius r ₂ ′ (ω) circumference to be corrected in a direction away from the center of the circle. It is moved to the point Q ₂ of the above. Here, r ′ (ω) can be expressed as follows.

r ′ (ω) = αf tan ω (0 ≦ α ≦ 1)
Here, ω is the half-angle of the subject, and f is the focal length of the imaging optical system (in the present invention, the zoom lens).

Here, if the ideal image height corresponding to the circle (image height) of the radius R is Y,
α = R / Y = R / ftanω
It becomes.

  The optical system is ideally rotationally symmetric with respect to the optical axis, that is, distortion is also generated rotationally symmetric with respect to the optical axis. Therefore, as described above, when the optically generated distortion aberration is electrically corrected, the radius inscribed in the long side of the effective imaging surface around the intersection of the optical axis and the imaging surface on the reproduced image. The magnification on the circumference of the circle of R (image height) is fixed, and other points on the circumference (image height) of the radius r (ω) are moved in a substantially radial direction to obtain a radius r ′ ( If correction can be performed by moving the concentric circles so that ω), it is considered advantageous in terms of data amount and calculation amount.

However, the optical image is no longer a continuous amount (due to sampling) when captured by the electronic image sensor. Therefore, strictly speaking, the circle with the radius R drawn on the optical image is not an accurate circle unless the pixels on the electronic image sensor are arranged radially. That is, in the shape correction of the image data represented for each discrete coordinate point, there is no circle that can fix the magnification. Therefore, it is preferable to use a method of determining the coordinates (X _i ′, Y _j ′) of the movement destination for each pixel (X _i , Y _j ). When two or more points (X _i , Y _j ) have moved to the coordinates (X _i ′, Y _j ′), the average value of the values possessed by each pixel is taken. If there is no moving point, interpolation may be performed using the values of the coordinates (X _i ′, Y _j ′) of some surrounding pixels.

  Such a method is particularly distorted with respect to the optical axis due to a manufacturing error of an optical system or an electronic imaging element in an electronic imaging device included in a zoom lens, and the circle with the radius R drawn on the optical image is It is effective for correction when it becomes asymmetric. Further, it is effective for correction when a geometric distortion or the like occurs when a signal is reproduced as an image in an image sensor or various output devices.

  In the electronic imaging apparatus of the present invention, in order to calculate the correction amount r ′ (ω) −r (ω), r (ω), that is, the relationship between the half field angle and the image height, or the real image height r and the ideal image height. The relationship between r ′ / α may be recorded on a recording medium built in the electronic imaging apparatus.

  Note that the radius R preferably satisfies the following conditional expression so that the image after distortion correction does not have an extremely short amount of light at both ends in the short side direction.

0 ≦ R ≦ 0.6L _s
Note that L _s is the length of the short side of the effective imaging surface.

  Preferably, the radius R satisfies the following conditional expression.

0.3L _s ≤ R ≤ 0.6L _s
Furthermore, it is most advantageous that the radius R coincides with the radius of the inscribed circle in the short side direction of the substantially effective imaging surface. In the case of correction in which the magnification is fixed in the vicinity of the radius R = 0, that is, in the vicinity of the axis, there is a slight disadvantage in terms of the actual number of images, but the effect of reducing the size is ensured even if the angle is widened. it can.

The focal length section that needs to be corrected is divided into several focal zones. Then, in the vicinity of the telephoto end in the divided focal zone, approximately r ′ (ω) = αf tan ω
You may correct | amend with the same correction amount as the case where the correction result which satisfies is obtained. However, in that case, some barrel distortion remains at the wide-angle end in the divided focal zone. Further, if the number of divided zones is increased, it becomes unnecessary to store extraneous data necessary for correction on the recording medium, which is not preferable. Therefore, one or several coefficients related to each focal length in the divided focal zone are calculated in advance. This coefficient may be determined on the basis of simulation or actual measurement. And approximately r ′ (ω) = αf tan ω in the vicinity of the telescope in the divided zone
It is also possible to calculate a correction amount when a correction result satisfying the above is obtained, and uniformly multiply the correction amount for each focal distance to obtain a final correction amount.

By the way, if there is no distortion in the image obtained by imaging an object at infinity,
f = y / tan ω
Is established. Where y is the height of the image point from the optical axis (image height), f is the focal length of the imaging system (in the present invention, the zoom lens), and ω is the image point connected from the center on the imaging surface to the y position. It is an angle (subject half field angle) with respect to the optical axis in the corresponding object direction.

If the imaging system has barrel distortion,
f> y / tan ω
It becomes. That is, if the focal length f of the imaging system and the image height y are constant, the value of ω increases.

  FIGS. 32 to 34 are conceptual diagrams of the configuration of a digital camera according to the present invention in which the zoom lens as described above is incorporated in the photographing optical system 41. FIG. 32 is a front perspective view showing the external appearance of the digital camera 40, FIG. 33 is a rear front view thereof, and FIG. 34 is a schematic cross-sectional view showing the configuration of the digital camera 40. However, in FIGS. 32 and 34, the photographing optical system 41 is not retracted. In this example, the digital camera 40 includes a photographing optical system 41 located on the photographing optical path 42, a finder optical system 43 located on the finder optical path 44, a shutter button 45, a flash 46, a liquid crystal display monitor 47, a focal length. When the photographic optical system 41 is retracted, the photographic optical system 41, the finder optical system 43, and the flash 46 are covered with the cover 60, including the change button 61, the setting change switch 62, and the like. When the cover 60 is opened and the camera 40 is set to the photographing state, the photographing optical system 41 enters the non-collapsed state shown in FIG. 34. When the shutter button 45 disposed on the upper part of the camera 40 is pressed, photographing is performed in conjunction therewith. Photographing is performed through the optical system 41, for example, the zoom lens of the first embodiment. An object image formed by the photographic optical system 41 is formed on the imaging surface (photoelectric conversion surface) of the CCD 49 via a low-pass filter F and a cover glass C that are provided with a wavelength band limiting coat. The object image received by the CCD 49 is displayed as an electronic image on the liquid crystal display monitor 47 provided on the back of the camera via the processing means 51. Further, the processing means 51 is connected to a recording means 52 so that a photographed electronic image can be recorded. The recording means 52 may be provided separately from the processing means 51, or may be configured to perform recording / writing electronically using a floppy disk, memory card, MO, or the like. Further, it may be configured as a silver salt camera in which a silver salt film is arranged in place of the CCD 49.

  Further, a finder objective optical system 53 is disposed on the finder optical path 44. The finder objective optical system 53 includes a plurality of lens groups (three groups in the figure) and an erecting prism system 55 including erecting prisms 55a, 55b, and 55c, and is linked to the zoom lens of the photographing optical system 41. The object image formed by the finder objective optical system 53 is formed on a field frame 57 of an erecting prism system 55 that is an image erecting member. Behind the erecting prism system 55, an eyepiece optical system 59 for guiding the erect image to the observer eyeball E is disposed. A cover member 50 is disposed on the exit side of the eyepiece optical system 59.

  FIG. 35 is a block diagram showing the internal circuitry of the main part of the digital camera 40. In the following description, the processing unit 51 includes, for example, the CDS / ADC unit 24, the temporary storage memory 17, the image processing unit 18, and the like, and the storage unit 52 includes, for example, the storage medium unit 19 and the like.

  As shown in FIG. 35, the digital camera 40 is connected to the operation unit 12, the control unit 13 connected to the operation unit 12, and the control signal output port of the control unit 13 via buses 14 and 15. An imaging drive circuit 16, a temporary storage memory 17, an image processing unit 18, a storage medium unit 19, a display unit 20, and a setting information storage memory unit 21 are provided.

  The temporary storage memory 17, the image processing unit 18, the storage medium unit 19, the display unit 20, and the setting information storage memory unit 21 are configured to be able to input or output data with each other via the bus 22 The imaging drive circuit 16 is connected with a CCD 49 and a CDS / ADC unit 24.

  The operation unit 12 includes various input buttons and switches, and is a circuit that notifies the control unit of event information input from the outside (camera user) via these input buttons and switches. The control unit 13 is a central processing unit composed of, for example, a CPU, and has a built-in program memory (not shown). The control unit 13 is input by a camera user via the operation unit 12 according to a program stored in the program memory. This circuit controls the entire digital camera 40 in response to the instruction command.

  The CCD 49 receives an object image formed via the photographing optical system 41 according to the present invention. The CCD 49 is an image pickup element that is driven and controlled by the image pickup drive circuit 16 and converts the light amount of each pixel of the object image into an electric signal and outputs the electric signal to the CDS / ADC unit 24.

  The CDS / ADC unit 24 amplifies the electric signal input from the CCD 49 and performs analog / digital conversion, and temporarily generates the raw video data (Bayer data, hereinafter referred to as RAW data) that has just been subjected to the amplification and digital conversion. It is a circuit that outputs to the storage memory 17.

  The temporary storage memory 17 is a buffer made of, for example, SDRAM or the like, and is a memory device that temporarily stores the RAW data output from the CDS / ADC unit 24. The image processing unit 18 reads out the RAW data stored in the temporary storage memory 17 or the RAW data stored in the storage medium unit 19, and performs various corrections including distortion correction based on the image quality parameter designated by the control unit 13. It is a circuit that performs image processing electrically.

  The recording medium unit 19 detachably mounts a card-type or stick-type recording medium made of, for example, a flash memory, and the RAW data transferred from the temporary storage memory 17 to the card-type or stick-type flash memory. It is a control circuit of an apparatus that records and holds image data processed by the image processing unit 18.

  The display unit 20 includes a liquid crystal display monitor 47 and is a circuit that displays an image, an operation menu, and the like on the liquid crystal display monitor 47. The setting information storage memory unit 21 stores a ROM unit in which various image quality parameters are stored in advance, and an image quality parameter selected by an input operation of the operation unit 12 among the image quality parameters read from the ROM unit. RAM section is provided. The setting information storage memory unit 21 is a circuit for controlling input / output to / from these memories.

  In the digital camera 40 configured in this manner, the imaging optical system 41 has a sufficiently wide angle range according to the present invention, and a compact configuration, while the imaging performance is extremely stable at a high zoom ratio and in a full zoom ratio range. Therefore, high performance, downsizing, and wide angle can be realized. In addition, fast focusing operation on the wide-angle side and the telephoto side is possible.

  The present invention may be applied not only to a so-called compact digital camera that captures a general subject as described above, but also to a surveillance camera that requires a wide angle of view and an interchangeable lens camera.

FIG. 2 is a lens cross-sectional view at the wide-angle end (a), the intermediate state (b), and the telephoto end (c) when focusing on an object point at infinity according to the first exemplary embodiment of the zoom lens of the present invention. It is the same figure as FIG. 1 of Example 2 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 3 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 4 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 5 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 6 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 7 of the zoom lens of this invention. It is a figure similar to FIG. 1 of Example 8 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 9 of the zoom lens of this invention. It is a figure similar to FIG. 1 of Example 10 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 11 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 12 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 13 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 14 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 15 of the zoom lens of this invention. FIG. 6 is an aberration diagram for Example 1 upon focusing on an object point at infinity. FIG. 6 is an aberration diagram for Example 2 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 3 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 4 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 5 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 6 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 7 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 8 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 9 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 10 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 11 upon focusing on an object point at infinity. FIG. 14 is an aberration diagram for Example 12 upon focusing on an object point at infinity. FIG. 14 is an aberration diagram for Example 13 upon focusing on an object point at infinity. FIG. 16 is an aberration diagram for Example 14 upon focusing on an object point at infinity. FIG. 18 is an aberration diagram for Example 15 upon focusing on an object point at infinity. It is a figure for demonstrating the basic concept for carrying out the digital correction of the distortion of an image. It is a front perspective view which shows the external appearance of the digital camera by this invention. It is a back perspective view of the digital camera of FIG. It is sectional drawing of the digital camera of FIG. FIG. 33 is a configuration block diagram of an internal circuit of a main part of the digital camera of FIG. 32.

Explanation of symbols

G1 ... 1st lens group G2 ... 2nd lens group G3 ... 3rd lens group G4 ... 3rd lens group S ... Aperture stop F ... Optical low-pass filter C ... Cover glass I ... Image plane E ... Observer eyeball 12 ... Operation Unit 13 ... Control units 14 and 15 ... Bus 16 ... Imaging drive circuit 17 ... Temporary storage memory 18 ... Image processing unit 19 ... Storage medium unit 20 ... Display unit 21 ... Setting information storage memory unit 22 ... Bus 24 ... CDS / ADC unit 40 ... Digital camera 41 ... Shooting optical system 42 ... Shooting optical path 43 ... Viewfinder optical system 44 ... Viewfinder optical path 45 ... Shutter button 46 ... Flash 47 ... Liquid crystal display monitor 49 ... CCD
50 ... Cover member 51 ... Processing means 52 ... Recording means 53 ... Viewfinder objective optical system 55 ... Erect prism system 55a, 55b, 55c ... Erect prism 57 ... Field frame 59 ... Eyepiece optical system 60 ... Cover 61 ... Focal length Change button 62 ... Setting change switch

Claims (22)

In order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power are provided, from the wide-angle end to the telephoto end. During zooming, each of the first lens group, the second lens group, and the third lens group moves along the optical axis, and the interval between the first lens group and the second lens group is reduced. The distance between the second lens group and the third lens group is widened, and the first lens group consists of a single lens that is a biconcave negative lens, or two lenses that are a biconcave negative lens and a positive lens. The second lens group is composed of two positive lenses and one negative lens, and at least one of the two positive lenses of the second lens group has an aspheric lens surface. ,
A zoom lens satisfying the following conditional expression:
16 <C _jw / h _1w <23 (1)
Here, h _1w is the height of the on-axis marginal ray at the entrance surface of the first lens group at the wide-angle end and the farthest distance in-focus state,
C _jw is the length on the optical axis from the first lens group entrance surface to the image plane in the wide-angle end and the farthest distance in-focus state,
It is. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
16 <C _jmax / h _1w <23 (2)
Where C _jmax is the length when the length on the optical axis from the first lens group entrance surface to the image plane in the entire use state is the longest,
It is. A brightness stop disposed at any position from a space immediately before the second lens group to a space immediately after the second lens group, the brightness stop being in the second lens group during zooming; The zoom lens according to claim 1, wherein the zoom lens moves in the optical axis direction integrally with the zoom lens. The zoom lens according to any one of claims 1 to 3, wherein the following conditional expression is satisfied.
0.25 <h _1'w / f _w <0.4 (3)
Where h _1′w is the height of the axial marginal ray at the exit surface of the first lens group at the wide-angle end and in the farthest distance focus state,
f _w is the focal length of the entire zoom lens system at the wide-angle end and at the farthest distance,
It is. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
1.0 <Σd / f _w <2.2 (4)
Where Σd is the sum of the thickness on the optical axis of each lens group of the entire zoom lens system,
f _w is the focal length of the entire zoom lens system at the wide-angle end and at the farthest distance,
It is. 6. The zoom lens according to claim 1, wherein a fourth lens group including one aspherical lens is disposed closer to the image side than the third lens group. 7. The focusing operation from the farthest distance focusing state to the short distance focusing state is performed by moving the third lens group in the optical axis direction. Zoom lens. By moving the third lens group and the fourth lens group in the direction of the optical axis with the mutual distance being constant or changing the mutual distance, the farthest distance focusing state is changed to the short-distance focusing state. The zoom lens according to claim 6, wherein a focusing operation is performed. In order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power are provided, from the wide-angle end to the telephoto end. During zooming, each of the first lens group, the second lens group, and the third lens group moves along the optical axis, and the interval between the first lens group and the second lens group is reduced. The distance between the second lens group and the third lens group is widened, and the first lens group consists of a single lens that is a biconcave negative lens, or two lenses that are a biconcave negative lens and a positive lens. The second lens group is composed of two positive lenses and one negative lens, and at least one of the two positive lenses of the second lens group has an aspheric lens surface. ,
A zoom lens satisfying the following conditional expression:
1.5 <f ₂ / f _w <1.9 (5)
Where f ₂ is the focal length of the second lens group,
f _w is the focal length of the entire zoom lens system at the wide-angle end and at the farthest distance,
It is. The zoom lens according to claim 9, wherein the following conditional expression is satisfied.
1.09 <| f ₁ | / (f _w · F _NOw ) <1.7 (6)
Where f ₁ is the focal length of the first lens group,
F _NOw is the F number at the wide-angle end and at the farthest distance.
It is. The zoom lens according to claim 9 or 10, wherein the following conditional expression is satisfied.
0.28 <h _2w / f ₂ <0.35 (7)
Where h _2w is the height of the on-axis marginal ray at the entrance surface of the second lens group at the wide-angle end and at the farthest distance focus state,
It is. 12. The zoom lens according to claim 9, further comprising a fourth lens group including one aspherical lens on the image side of the third lens group. The focusing operation from the farthest distance focusing state to the short distance focusing state is performed by moving the third lens group in the optical axis direction. Zoom lens. By moving the third lens group and the fourth lens group in the direction of the optical axis with the mutual distance being constant or changing the mutual distance, the farthest distance focusing state is changed to the short-distance focusing state. The zoom lens according to claim 12, wherein a focusing operation is performed. In order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power are provided, from the wide-angle end to the telephoto end. During zooming, each of the first lens group, the second lens group, and the third lens group moves along the optical axis, and the interval between the first lens group and the second lens group is reduced. The distance between the second lens group and the third lens group is widened, and the first lens group consists of a single lens that is a biconcave negative lens, or two lenses that are a biconcave negative lens and a positive lens. The second lens group is composed of two positive lenses and one negative lens, and at least one of the two positive lenses of the second lens group has an aspheric lens surface. ,
A zoom lens satisfying the following conditional expression:
0.8 <h _1w /IH<0.5 (8)
Here, h _1w is the height of the on-axis marginal ray at the entrance surface of the first lens group at the wide-angle end and the farthest distance in-focus state,
IH is the maximum image height,
It is. The zoom lens according to claim 15, wherein the following conditional expression is satisfied.
0.4 <h _2w /IH<1.2 (9)
Where h _2w is the height of the on-axis marginal ray at the entrance surface of the second lens group at the wide-angle end and at the farthest distance focus state,
It is. The zoom lens according to claim 15 or 16, wherein the following conditional expression is satisfied.
0.4 <D _2w / f _w <1.0 (10)
Where D _2w is the distance on the optical axis between the second lens group and the third lens group at the wide-angle end and in the farthest distance focusing state,
f _w is the focal length of the entire zoom lens system at the wide-angle end and at the farthest distance,
It is. The zoom lens according to any one of claims 15 to 17, wherein the following conditional expression is satisfied.
0.4 <g _3w / g _3t <0.88 (11)
Where g _3w is the height of the most off-axis principal ray at the entrance surface of the third lens group at the wide-angle end and the farthest distance in-focus state,
g _3t is the height of the most off-axis principal ray at the entrance surface of the third lens group at the telephoto end and at the farthest distance focused state;
It is. The zoom lens according to any one of claims 15 to 18, further comprising a fourth lens group including one aspherical lens on the image side of the third lens group. 20. The focusing operation from the farthest distance focus state to the short distance focus state is performed by moving the third lens group in the optical axis direction. Zoom lens. By moving the third lens group and the fourth lens group in the direction of the optical axis with the mutual distance being constant or changing the mutual distance, the farthest distance focusing state is changed to the short-distance focusing state. The zoom lens according to claim 19, wherein a focusing operation is performed. 16. The zoom lens according to claim 1, and an imaging surface disposed on an image side of the zoom lens, wherein an image formed on the imaging surface by the zoom lens is converted into an electric signal. An imaging apparatus comprising: an imaging element.

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